Well, you know how it is not the intake that really is the problem? Just the flow? Which most filters do not come adjustable (asides from Marina I think it is, which has 2-3 separate slots for the actual cartridge, and has an adjustable flow) First I thought.... what about a hood that has a bowl-like spot where the flow hits? With the right amount of holes drilled (acrylic) it could go through still, but would become more like rain - which I may actually use something similar for breeding x)
Anyways, instead, have it similar to a breeder's box - where it attaches by hooking onto the side of the tank, but keeping it so the filter fits ontop without problems. I'd have to try this out many many times to get the right amount of holes to the certain size of filter to avoid over-flowing, but that could work?