This is the best option I feel.
1, he is pretending to a Bright student, and they all learned mobile suits, if he can't pilot the mobile suit well first shot that's a way to have his cover blown. He'd probably want to avoid that. He can use getting used to an older non mobile suit Frame as an excuse.
2, it's got no paint, meaning he can personalize it later.
3, chain gun, just aim in the general direction and unload, no perfect aim necessary. Hammer, just Smash, no finesse of a blade.
4, the mono eye is cool, and the armor means can take more of a beating.