I have watched this and was not sure about joining in b/c it ends up going the same way often . . .
FIRST for artillery use I have not seen 2 important factors mentioned . . . pre-plotted hexes and adjusting fires.
I will address these in reverse order . . . adjusting fires is a important factor in the tactical use of artillery as it allows you to gain accuracy firing at a target. The earlier mention of using artillery to make a "wall" to keep enemy units from passing through the 'beaten zone' (technical term) is a IRL tactic (but it makes infantry & cav pucker . . . just how good was the quality control on shells/propellant? Are those Fat, Dry, & Comfy arses actually putting in the numbers right?) that has been used in multiple battles in history. But you need to be 'mostly' accurate to hit that zone and as the person who suggested it said you need to have fast forces to exploit that opening you create.
This is also why I favor artillery units with deeper ammo bins, think Sniper is the best, and use Sniper/Thumper almost exclusively for unguided munitions. The 5 rounds a ton you get with A4 & Long Tom just IMO does not let take those ranging shots. A TAV with a ton of smoke is useful for throwing that smoke but also "finding" that hex you want to hit as long as it can be observed to get the -1 TH for each follow on shot.
Pre-plotted hexes are easy . . . the old MM servers had the default of 4 hexes pre-plotted that were auto-hits for your artillery. This made it very easy to deal with the 'best' camping spot for your opponent. It can do the same for table top- you can select the woods on a hill, or to be devious the gap between some hills they will have to move through to get to the middle of the map. But this depends on if your table is using this part of artillery.
Finally some of the things I did not see address for artillery options . . . and usually not done on tables- can you destroy or set on fire buildings/woods? If so you can of course blast away the buildings/woods and make rubble hexes. While a hex of woods on fire is not going to deter a Thunderhawk (or a Gargoyle Prime . . . I once had someone hit a Gargoyle with the old inferno rules), it can most other things b/c your long range snipers mix ERPPC/ERLL with Gauss or LRMs.
But to address some generic points for the OP principles of deployment in artillery & AA are much the same. You want mass, mix, mobility, and integration . . . integration does not really count in BT b/c for the most part we do not factor in the ability to clearly communicate between spotters & guns nor is there a good means of setting up combined arms vs distinct forces. My favorite example of this is the nova vs a star of Omnis & a star of BA. In table top- TW or AS- terms both have the same abilities effectiveness but the Nova should outperform the two individual stars that are working together.
Mobility is a wash too though I prefer it b/c I usually have my artillery on the battlefield. It used to be more handy to make 'adjustments' but can still be done between indirect fire over 17 hexes and then moving forward the next turn to indirect or if the artillery unit is sturdy enough, direct fire the same location. If I was 'designing' a combat command I would of course prefer self-propelled artillery and one of the things I miss from MWDA's options is the ability to tow guns . . . though now we have trailers (though unfortunately all the old vehicles have no 'hitch' though it is a standard bit of design . . . ) which means you can move artillery strategically with cargo vehicles.
Leaves you with mass- as in massing guns- and mix. Massing the guns is pretty self-explanatory but the key factor for BT table top is that you get a sufficient amount of guns for the BV used and map size. IF you are good with artillery AND spend some BV (aka gunners) you can get by with less guns. IMO the minimum is three for most people and four is the safest. The least I will personally bring is two- and those generally have to be two different units. Yeah, the Demolisher A4 & Naga are useful with their two pieces on the same unit but it just invites Murphy to play with the 'random' damage you get. The other thing I would do with just 2 artillery units is use field guns. The BV on these is LOW but they only have 1 ton of ammo per gun and IIRC the field gun artillery has to use all the same type around- IE, no having a 2 Thumper field gun platoon with 1 ton HE and 1 ton Copperheads.
This leaves mix, which IRL is about a mix of systems so you get the same sort of synergy combined arms gets you in a maneuver unit. IRL that means ideally you would like tube, mortar, rocket, and perhaps even missile artillery though the later has faded in modern times as rockets became more useful. For the purposes of BT that applies to the type of rounds. Look at the Ballista SP Artillery Tank- 3/5, decent armor, Sniper w/3 tons of ammo- it makes it very easy to mix artillery options. With my 3 'gun' minimum I get 9 options for munitions- say each SP gun gets 1 ton HE, SP gun A gets a ton of cluster, SP gun B gets a ton of Copperheads, SP Gun C gets a ton of Fuel Air Explosion (there you go Daryk), and you still have 1 ton on each SP gun to customize. IIRC, the HE round also works for AA duty?
Or you have 2 Ballistas and get something with a single A4 launcher that has more than 3 tons of ammo- HE, Inferno, FASCAM. Now you can blast, smoke, burn, mine, and go for the head hit in one package.
But other ideas for the OP- like I said, can you catch woods on fire? Burn them out of the camping spots. Someone mentioned Thunder Mines, and that is a good option, just get the density to 20 for each of those expected camping hexes and they will have to risk a PSR to get to the camping spot . . . and maybe internal damage to the leg.