I understand that we have discussed alot of the strategy of planetary assault/defense to death in the past. However, from my understanding only one class has been desginated, in detail, as a vessel designed for "amphibious" actions. This vessel being a size 4 wyrnee class from the first Spacedock ship book, which was an overview of Starfleet Vessels. I have to wonder whether that is sufficient enough.
Would they modify already used spaceframes for amphibious capabiliy, or create new designs specific to the mission.
Either way, spaceframes that would be designed for amphibious missions would have a larger amount of the following:
Sparse Crew Quarters
Transporters
Medical Facilities
Shuttlebay Facilities.
This way they can carry the large complement of ground forces ("marines", if you wish in your universe) to conduct the assult/defense; be able to transport a larger number of marines prior to the enemy activating their transport inhibitors; increased medical facilities to provide medical care to wounded; and a sizable number of shuttles in order to deliver and evacuate personnel when transporters are not an option.
Would all that be able to fit in a size 4 vessel? Maybe if it only carries a ground forces complement the size of a 1 or 2 platoon(s) (40-80 passangers).