it needs to be optimized to transport heavy vehicles and light infantry with battlearmor.
It also needs to be able to haul light vehicles, and Powered Armor infantry.
Timeframe is 3055-3060, location is Lyran.
Fluff-wise, it should suggest 'multiple terrain takeoff and landing' and it should be convertible to ASF transport/launch as carrier mod.
So instead of something completely new, given your requirements, my first thought is to actually make this a "variant" of the newly introduced in 3053 Hercules class Dropship that is the Lyran's version of an Excalibur "Light" or a Triumph.
Per Sarna & the TRO the starting load of the Hercules as follows
Crew Deck above Vee Decks: Vee Crew Quarters + 12 Infantry Platoons
Upper Vehicle Hold: 24 HvyVeeBays,
though its loading ramps cannot support more than 75 tons. (Fluff Quirk of Ramps not moving Assaults)Lower Vehicle Hold: 12 HV-Bays for any size vehicles.
Cargo Bay: 1,381 tons
While you wanted it to be a 2 separate variants, my initial thoughts is you can swap out 24 Heavy Bays for 12 ASF & 12 Light Vees as a combo unit.
Otherwise you have the tonnage for 4 Squadrons of ASF w/o any Tanks.
The Infantry is also a fairly easy swap.
Reduce the Grunts by 3 Platoons for 3 Platoons of BA paying for it w/ a bit of the Cargo Bay.
Fluff it as Bowie licensing your company the production rights & then they create the variants.
So we have Option-1 = 12+12+12 above.
Option-2 = 24 ASF
Option-3:
There could also be the idea of keeping up production of the original model which is where you get your Heavy Vees & Foot Infantry from.
And then you have another variant that swaps all that out for the Light Vees, ASF, & BA you want.
Say 18 ASF + 12 Light Vees + Battle Armor Battalion (Less Cargo) (Or a Company + added Cargo)
The Herc is clearly a support ship, the armor is thin, its NOT at all an assault ship & weapons are decent but nothing amazing.