Well, horizontal distance does have an effect on "head pressure", I think its 10 feet of horizontal distance equals 1 foot of vertical distance, or something like that. Not really enough to bother me, I don't think.
Here's another possible sump idea. This is in case the 10g tank doesn't fit above the 55g tank inside the stand.
In this design, I would have a horizontal pipe distributing the water across a bonded filter pad, sitting on top of a denser filter pad, sitting on top of a 100 or 200 micron filter pad. This would sit on top of a drip plate, on top of the biochamber. The water would drop through the bio media, then move into the next chamber, which I will either leave empty, use for bags of activated carbon, stuff with coarse sponges, or use as a fw refugium to grow plants for nitrate consumption. The water then flows over another wall and under one last one to the pump chamber, and then is pumped back up to the tank.
I think I prefer the first design above, but if I can't do that then this one will work as well.
