for tubs I have had luck buying one trailer fender at tractor supply, then cutting it in half to make two tubs. I take the piece I cut out of the sidewall and tack weld it into the fender, closing it out.
IMG_6890 by
Joe Doh, on Flickr
make sure you dont buy the GALVANIZED tubs, welding on galvanized is a good way to get sick.
2" clearance to the axle isnt enough, you will bang the frame just driving regular, better stick to the plan of a small notch.