I’m currently using T-slot aluminum on my rig and it’s held up great through a full season so far. No issues with SH exposure. Aluminum itself handles chemicals just fine.
The bigger concern is rust/corrosion, not the SH. Make sure you match material types on your fittings, or use a sacrificial anode if it’s a bigger project and you don’t have the fittings to match.
A lot of my frame is built with T-slot for the ladder rack and load bearing side shelves and it’s been very solid from a load-bearing standpoint too. I did pre-treat everything with an aluminum polish/coating as a precaution. Hard to tell how much that has helped, but it hasn’t hurt.