well, maybe your right about the outboat, ive cheked out other micro boat threads and found the back is almost underwater, even with a inboard direct. The brushless idea sounds good, plus i found a 600 flex or direct drive setup(withprop) for around $60, and a 700sc for 48 dollars. here are the links
http://www.offshoreelectrics.com/MainPage.htm you need to klic on motors & mounts to get to the page
you will find a 600bb,700sc,and three types of brushlesses
also I have found a 29'' ABS hull with tons of room for only $25
here is the link
http://www.hobby-lobby.com/vhull.htm
Also I need some tips about the speed controllers and servos, along with radio gear, for the brushless and brushed 6 $ 700's