I would stay away from the pressure treated and instead give it a coat or two of exterior latex paint. The pressure treating will protect from rot but does nothing to keep the wood from splitting, checking or absorbing water. Plus it adds considerable weight. Splinters from pressure treated wood will fester and easily become infected, not what I want on a remote trip.
I would consider using T-nuts and pan head cap screws instead of the countersunk bolts. Easier to install and you don't need to cut them. Check out the modular chain link fencing stuff at Lowes or Home Depot. There are bolt on Tees and Elbows that could be used to fashion a foot rest. (I made a bolt on casting platform for my cataraft)