OK...first, you don't really need a bubble trap on the front end of the
fuge. it'll take up more space than you have (trust me, i've built several 10 gal
fuges).
don't worry about having too much outflow for the pump. the pump determines the flow from the tank. as long as the siphon breaks on your return and outflow lines, the
fuge won't overflow.
you can drill siphon break holes in your intake/outflow fittings so they sit about 1/4" to 1/2" below the water surface. these will break the siphon in the event of a power failure or if you need to stop the pump.
a single overflow will run about 300
gph, so your pump should be sized with that in mind. remember to take head loss into consideration.
