Your basic Hunter tank is a great pairing for infantry. LRMs have the range infantry lack, and if need be, the infantry can spot for indirect LRM fire.
I like the way of your thinking. It also makes good fire support unit for any tank from Scorpion and Galleon all the way up to Manticore, Demolisher, and Schrek. Best tank to pair it up with is Vedette becouse those have equal speed. Armored cavalry company: 4 Hunters and 8 Vedettes.
Note: Hunter is Lyran made vehicle. In 3028 Federated Suns could have got some through trade.
BattleDroids (original game edition) rulebook has extremely simple rules for vehicles. There Hunter is described as assault gun armed with Autocannon 5.
Maybe include a Hetzer and keep it in reserve as a nasty surprise to any mechs trying to finish off the infantry with MGs or hunt down your long ranged tanks.
Keep in mind that Hetzers come with wide variety of different weapons. Hetzer battalion (mentioned in some TRO) isn't as stupid as you'd think when some of the Hetzers are LRM and AC/10 variants.
Don't forget APCs: take 10 ton wheeled APC from TRO/RS 3039, remove infantry compartment, MG, and half ton MG ammo, add SRM 2 and full ton of SRM ammo. There we have armored car. Remove MGs entirely and we've got enough tonnage for SRM 4 or LRM 5. Comparable APC refits exist in reality too. RS3039 Unabridged has missile variants too, but those remove MGs and maybe some armor while keeping the infantry compartment.
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To get better understanding what factions have what vehicles (book has also 'Mechs and aircrafts), it is best to buy Techincal Readout 3039 and read from there. Statistics for only one model of each unit, but since you already have got Unabridged Record Sheets... Oh yes, that book and RS don't have all the vehicles that are available at the time. Other vehicles in 3028 I remember from top of my head:
Brutus (heavy tank in Capellan Confederation)
Flatbed Truck (armored cargo truck)
Heavy APC serie (20 ton APCs, can fit up to two foot platoons OR one foot platoon and some heavy weaponry)
LTV-4 Hovertank (already mentioned this, in XTRO Primitives 2, widely available at all times)
Some more that come between 3028-3039:
Po (heavy tank, Capellan Confederation)
Zhukov (heavy or assault tank, Capellan Confederation)
Consult Master Unit List what is available when. You still need TRO to find out who have access to that unit.
To get you started with vehicles[edit2]
When your players encounter faction specific units, it gives them better immersion where they are.
Lyran Commonwealth: Savannah Master, Hunter, Drillson, Sturmfeur
Draconis Combine: Saracen, Scimitar, Saladins
FedSuns: Striker, Goblin
Capellan Confederation: Brutus
Free Worlds League: Harasser, Ontos
Most other (ground) vehicles are available for more than one faction. FWL makes Galleons, but apparently it sells those to others. Pike is made in Magistracy of Canopus, but those are sold pretty much to everybody. Quikscell's vehicles (Hetzer, 60 ton tracked missile/weapon carriers, some others) are made pretty much everywhere. Bulldog tank is made at least in Capellan Confederation and Draconis Combine, but FedSuns had acquired those in significant numbers just before collapse of the Star League and has got more through raids and conquests. Everything Lyran Commonwealth and Federated Suns make can have exchanged ownership through trade ever since (and before) first signing of Federated Commonwealth alliance in 3023 (if I recall correctly). And so on and so forth.