Painting Underside of Tub

I spent an hour wrangling the tub onto the frame. Getting the mounting flanges on the underside to line up with the slots I cut in the steel plate covering the frame is always a challenge. Once I was seated properly I drilled new holes in the mounting tabs around the outside of the frame and bolted down. Once I knew it was going to fit ok, I took the tub back off and painted the underside of the tub and the top of the frame plate. I want to "permanently" mount the tub for the remiander of fabrication. Once the lid, rack, spare tire mount etc are all mounted in place its going to be to heavy to take on and off for painting.