Here's a few solutions I can think of:
1) Closed loop. This requires either drilling or priming an external pump, but it keeps pumps out of your tank.
2) "Mod'ing" a Maxijet so that it's held to the glass via one side of a Magfloat as opposed to suction cups or hanging brackets. This makes the Maxijet MUCH smaller.
3) Building a false wall on one corner or side of the tank to hide your powerheads. This usually requires a lot of work though and is best done with an empty tank (in which case you might as well go closed loop).