Thanks! I found that Durso standpipe earlier and have started incorporating it into my design. I'll post pics when it's all done. Just a note to anyone reading through this:
When measuring the length of your baffles, use the inside length of the tank, NOT the outside. I don't know why, exactly, I used the outside length, but it didn't work so well. I was able to insert the baffles, with some heavy force, and apply the silicon, but eventually they put so much pressure on the tank walls that when I went out to check on their progress they had shattered the walls of the tank. GAH!! There goes 12 hours down the drain.
SO I had to buy a new tank, remove the baffles from the wreckage of the old one, cut them down to proper size and then start over. Fortunately, this whole process has given me time to figure out how to do the overflow tank properly and everything has now been assembled. I am just waiting for the adhesive to finish curing and I can test the whole set up with a bucket. Wish me luck!