I stand developed (stood developed?) 4x5 in the following manner. I used the absolutely cheapest 5x7 trays available which are flat bottomed and have a very low profile and put one negative in each one, face up, in 500 ml of dilute rodinal (I ain't gonna mention the dilution 'cause it was just too crazy weak and Lex is gonna yell at me.) On top of those trays I put a deeper 11x14 tray, flipped over so that the 5x7's were cacooned beneath. Then I layored three towels on top of that, patting down the edges as best I could before turning on the lights. That arrangement proved light tight indefinitely -- or at least for 7 hours, which was the length of my longest test.
Before trying this, I'd read another post on P.net which mentioned that old-timers floated trays on liquid mercury (!) for stand development to assure the neg was perfectly flat. Because of this, I thought for sure I was going to get un-even development, but it just never happened. All together the test turned out very promising.