Other than my deployable structures idea, I have a few thoughts.
1, a speed form for rapid transit, low armor, weapons limited to bombs and light mounts.
2, an assault form, weapons locked to forward fixed mount, no light mounts, heavy armor and mounts in abundance.
3, archer form, missle and balistic mounts in abundance, wide body.
4, support form, weapons array set up for area denial, pd, and sniping, very high flux capasity.
Forms above (cept for the first) could be deployables, stationary stations to reinforce objectives.
From an ouside the game point of view, a larger form is easier to live in, a smallet one is harder to hit.
matter ammout remains constant, so smaller form is tougher.