Thanks for the suggestions -- I'll file them away for now, till I'm ready to add fish.
Although I did see a fuzzy dwarf lion at a LFS today, which looked awesome!....so that could win out.....
As for the build, I got the eHeim 1250 pump yesterday, and took another look at my sump situation. I'm pretty sure the panels I have are just too short to glue in place, so I think I would need to get new panels if I wanted to go that route (which I had hoped to avoid).
Going back to my other idea, I picked up a Kritter Keeper which fits pretty nicely on the right side. It's about 11"x6"x8". I *think* it could work to run the pump in that. Here's a pic:
Another wrinkle, though, is that all of the LFS people have been telling me that I should have a much larger pump to account for head-loss, bends in the return and the possibility of needing a chiller. I think they're standpoint is that I should be achieving the 10x, 20x, 20+x turnover rate with my sump pump to reduce the # of powerheads I need and therefore reduce the total heat I'm adding.
All kind of makes sense, but I've seen a lot of articles that recommend only 3x to 5x turn over through the sump so............not sure. I think I'll wait till I get my overflow and see how the pump pressure matches up with the out flow. If They match up well, I'll probably just go with it and adjust as needed later on......
Anyway (sorry for rambling), thanks for any more comments / suggestions!