Thank you for your input. I do like the idea of stacking the trays. I had thought of if at the beginning but I figured it had a major drawback as I hadn't seen them mentioned anywhere, even by those with small/cramped darkrooms. If everything goes well, I will start and finish the darkroom this coming weekend. I already upgraded the fan to a quiet, high efficiency unit, the only drawback is I won't be able to install a secondary fan for positive pressure in the darkroom---hopefully dust won't become an issue. I also have the hardware to get the water from the tub's spout. I also have a couple of rolls that I already developed, ready to start playing!
The cross contamination makes sense. I thought the amount of developer in the wash(with continuous flow) would be so minimal as to not be an issue. I'll look for a way to test for that.
The reason use the washer as a "stop bath" is because of room, I don't have much flat surface area to put all the trays(in the sizes I would like).
The washer would be running anyways since I will need to wash the prints. I actually got a very nice assortment of trays with the purchase of the washer so I will be able to use the appropriate size to minimize chemical waste. As far as the developer tray placement, it was put there just for the benefit of showing an image---a picture is truly worth a thousand words!
I just don't have the room to have a separate tray for the washer's overflow.