You'll need a custom Dropship, likely an upgraded Mule for the sheer cargo capacity.
Are you planning on doing raids, or longer-term assaults? If doing raids then plan for being on-planet for only a couple hours, and if taking longer then the loot should be a minor part of your paycheck.
Specific parts, assuming you are just planning on raiding and leaving:
Drop the full flight company and dozen conventional fighters. Just 2 ASF should be sufficient, and if you have to leave quick then those conventional fighters will be left behind. This is based on the Union having 12 Mechs and 2 ASF.
The ADA and artillery should only be put next to the Dropship to keep it safe, so the infantry is a good idea. Maybe 3-4 hexes away to avoid most splash damage from enemy artillery.
The Scout company of a dozen 5-ton hovercraft will give you fits as you have to pick one of the following options for carrying them in the Dropship:
- carry them as 60 tons of cargo, but you have to prep them after you land before they can go out
- carry them all in Light Vehicle bays, requiring a total of 600 tons
- some mix where a few are prepped in LVBs before you land, and the others are hauled from cargo to be prepped
The Engineering group should just be a pair of bulldozers whose only job is to make berms so enemy artillery has reduced area effect damage.
Medical should be emergency recovery vehicles to bring back wounded people to the Dropship, rather than setting up MASH in the field. Ambulances rather than surgical theaters. Mobile Kitchens should be on the Dropship rather than needing to deploy. During the mission your troops should be either using rations, or enjoying bag lunches prepared at the Dropship's kitchen.
Command van + air defense for a Mech Company with lots of hangers-on? If raiding, use your Company Commander's mech as the command unit, with the Dropship having extra Communications equipment to do some processing. Most of your stuff will be near the Dropship keeping it safe, so the Dropship can serve as the Command 'van', while the Mech force just has the Company Commander telling the hovercraft force commander where to go, or the ASF pair leader where to patrol. After you get bigger (~3 Mech companies) then you look into a command van.
Security troops should all be motorized/mechanized so they can withdraw back into the Dropship real quick when the locals decide to crash the party.
Screening hovercraft might be a good idea. I'd start with 4 of them to serve as a roving patrol/defense force at the Dropship, or even coming along with the Mechs.
Small semi-trucks would be good for loot, larger ones for Mech recovery. Some of the smaller trucks should be hover depending on the local terrain.