Just try various wattages until you get to the right hieght and wattage to make the basking area in the mid 80's during the day. A specific wattage is impossible to give, since factors like air conditioning and such can change from house to house.
Don't bother with a UVB light if you are going to put the guy outside in a pen this summer. He'll do fine for a month or two without UVB.
That bin is the same one I use for quick temporary or hospital setups with my boxies. I've also used it as a nesting bin once. Should work out well for a single adult for a short time.