I was just out in a trailer that I use for storage, scrounging around for a big piece of aluminum that I remembered saving to use as a stressed panel across the bottom of my chassis. After measuring it, it is large enough to do what I planned. It's 0.063" Alclad 7075-T6 which is really strong-- its ultimate tensile strength is equivalent to 0.076" 1020 cold-rolled steel. I just washed it off and the next step is to take it into the shop and lay it on the upside-down chassis and draw an outline to cut it to size.
I found a few lengths of 7075 angle, too which should be useful for making brackets for brake line fittings, etc. Lunch time so I'm taking a break.
Whew, it's getting hot; 94F here already but it is supposed to reach 105F in town today. We are a little higher that the city; we are at 3,000 ft here in Diamond Bell Ranch. I can tell the humidity has risen a little here.
Regards, Neil Tucson, AZ