I have used light vehicle tactics successfully, in many games. The first thing is to realize that the more units you use, the harder it is for your opposition to deal with it. Second, that each one of those light units has a different advantage, and setting up a game that favors that advantage, where the opponent feels trapped, or railroaded, is when the tactic causes anger.
So, first mix it up a little -- one lance of Savannah Masters, or Gabriels is fine....per about 4000 to 5000 BV2. At that point, it is replacing one or two fast light mechs.... which, as long as the rest of the force is fairly balanced against the opposition, shouldn't be a major issue. Especially if there is enough terrain on the table, that it isn't all about the fast hover tanks.
I would also note to your opponent, that you do use combined arms, so that they know that the possibility is there ..... that way, they can have a few LBX armed mechs, or similar. I once had an opponent use 18 Savannah Masters, along with other units, on the table, against me --- (there was more than one person per side, but he and I had created the forces), but, as I knew that there was the possibility, I was able to field a Wolftrap, which is an awesome hover tank hunter, and an Assassin, the variant with the LBX5. It was still a hard battle, but because my side had some knowledge that we might face that, we were able to include something to deal..... so it wasn't a total kick in the seat.
Finally, spam is never good ---- in the above scenario, the planet in question, had just gotten the Savannah Masters, as a means to police shipping over some fairly large shallow inland seas.... so it made sense, and since we were attacking right after they were delivered..... their pilots were average 4/5 gunner pilots, rather than elite, but they did just happen to be together, rather than spread out in pairs in the 9 districts..... (that was how we justified them all on the field) ---- but, outside of this rare occurrence, spam is bad. It's one thing if you run into a militia with a lance of Scorpion Light tanks, a lance of Savannah Masters, and maybe a couple of other Hover tanks, plus some older tech, or sub-optimal mechs..... with a couple of better designs, to give a little spine..... or you instead run into a pair of Hellstars, supported by a battalion of Savannah Masters.
In the end, you CAN play with the swarm rules, but really, it falls under the Don't be a Dick rule....
My Comstar defenders once had 8 Gabriels, 2 Pike Support Vehicles, and 2 lances of mixed light and Medium 3025 defenders, versus an Equal BV2 mercenary company of mechs...... one of the merc lances were 3050 upgrades, while the rest were 3025.... and it was surprisingly equal ---- and everyone had a good time, while a couple of players learned respect for the Pike.
So, go ahead and do it, but keep some thought into what you do.
Nahuris