m troniks do some very small esc's - with it being a 380 size motor then you should be fine with one of their eco range, - i guess the eco 15 should be fine, inputs upto 12 volts and 15amp continuos output rating, the ' marine ' types go into reverse straight away ( no brake type system as with buggy esc's) and all are BEC enabled,
as for size then they are a simlar size to a standard 2 channel rx........at a guess about 40 mm long 30 mm wide and 15 mm in depth....
check them out at
http://www.mtroniks.net/