I would take this to a sandblasting shop and have all that rust removed because it's the "foundation" of all the work you intend to do later on. ...
I spent a lot of time online and the phone trying to find a sandblasting shop near me, they are all shut down due to you-know-what.
Ok, Now that it's roughly stripped down to the frame, there is a lot of rust, but no visible rot. I flipped it over to sand the bottom first.
I have done some sandblasting before, both in a box and with a compressor and siphon feed.
This is my current sandblast setup using Black Diamond Medium Grit from Tractor Supply, brand new gun, also TS and my neighbor's bigger newer compressor:
I had hooked up my smaller compressor, a Kobalt horizontal from Lowe's that has worked fine on everything else I needed it for, but failed for some unknown reason (which may be electrical)
Anyway, I can't make it work. The compressor is putting out plenty of pressure and air, but every time I squeeze the trigger, I get one 1/4" spurt of grit then no more, but when I lift it up, it pours out a ton through the tube back into the bag.
It must be something simple, right?