The most obvious problems would be rot and weathering. Somewhere close behing would be the issue of keeping everything flat. Does anybody outhere have experience with this?

One thought was to put a bench on wheels and store it in the shed. But that creates its own problems and you still have environmental extremes.

This may not answer your question directly, but it may give you some ideas.

I am building a boat outdoors in Southern California at a place where the yard is paved concrete.

Needed a place to layout bulkheads which could be as large as 12' x 16', consisting of 4x8 plywood sheets assembled to form the large panel.

Built a bunch of saw horses from reclaimed pallets.

On the saw horses, assembled some 2x6x20 ft timbers on a grid sort of like a system of floor joists in a house using bolts and fender washers to hold everything together.

Have basically ended up with a 12'x20' floor joist system about 36" high and exposed to the weather.

No snow, but lots of UV from the sun, lots of water when it rains, and lots of epoxy drips from me.

It is about 3 years old and is holding up well.

When I'm finished, it won't owe me anything.

You might consider something similar, maybe give it a couple of coats of wood preservative when you build it.

Expect a 3-5 year life and then build a new one.