If you're going to be a vehicle squad, you're probably going to be trying to hog all the vehicles - air & ground - so why not just put them all in the same squad? The helis only realistically need like 3 people dedicated to them max(depending on the map). Tank squads often don't even have a third guy just spotting people, so they probably would need like 4 people to effectively man most tanks on the map? This isn't even accounting for the fact there WILL be multiple vehicle squads.
Just combine them into one type so it looks nicer and puts more like minded people together.
I would also recommend giving vechicle squads faster spawns onto heli's and tanks so they can hop in them first since they're the squads who are specifically dedicated to them (instead of 2 seconds for example, reduce it to 1) Kind of silly to be the heli squad, but then one bozo from a recon squad nabs the heli slightly before you and uses it to jump on a tower and not transport anyone (that's me).
To balance it out maybe only have like 3-5 vehicle squads allowed in 127's. Reduce that number down in 32s & 64s. There literally aren't enough vehicles to support more than like 2-3 squads anyway most of the time, so why not give the dedicated peeps better spawn in times on tanks and helis (only in spawn)?