I was just wondering, is the only reason you dont want to put the fuge under the tank is because you dont want to drill the main tank? I am not an expert on this but couldnt you use a overflow on the main tank to move the water?
about a year ago I was going to put a sump/fuge on my 29 gallon tank. I was going to use an overflow and the 10 gallon was going to go under my tank. I didnt really know how to build a sump/fuge so I had a friend of mine do it for me. The problem we ran into was that the 10 gallon wouldnt fit in my stand so he took off the plastic braces that are on top and the bottom of the tank. When he did that the tank did fit in the sand and it was a tight fit but it did fit just right, at least that way it would help support the tank and it wasnt going to be full of water anyway so that way if something happened it wouldnt overflow. Unfortunately I became sick and had to give up my tank so I never had the chance to set it up. The way the sump/fuge was built of course was so the water would come in one end and at the other end I was going to use a mag pump or a large powerhead (cant remember for sure) to pump the water back to the tank. My friend did a really good job building it but I dont have pictures and I dont have it here where I live. I will see if I can get some pictures of it this weekend if it would help. I just think the fuge would be better if it was under the tank then next to the tank but that is my own opinion. also the rubber bin would work for a fuge, could you fit that under your tank? Sorry I cant answer the other questions but I am sure someone can. I have also read stuff about drilling a hole in one of the lines so if the pump fails it would stop the flow but I am not really clear on that. I know this probably wasnt much help, I just wanted you to have other options than putting your fuge next to the tank. Good luck!