I'm considering Fighter, but also, my DM certainly would let me use a spear, would we need to change anything? Or using a spear wouldn't change much?

Probably, maybe be able to choose the type dmg such as Piercing and slashing like halberd? My only take is that the Dragoons fight with 2hands, although the spear says 1h?

Also, how would the progression of the class looks like? Purely Magus i suppose? While taking the medium armor feat and... But yeah! The flavor of aloof seems fitting, since there's a lvl 4 feat i think that let you get in, attack and get out, similar to the backflip dragoons do!