We also wipe down after each use so the walls are not a problem...takes about 1 or 2 minutes.
The base part (ours is also a tub...a tiny bathtub) and for that I use
Comet Bathroom Cleaner/soap scum remover....spray and let it sit maybe 10 minutes max while you go have a cool beverage. I spray it well but not so it is dripping into my tank. I put a cloth down by the drain. I don't want it in my tank. It is not fumy or bleachy smelling also. Then I wipe it down with either paper towels (and pitch them immediately) or a cloth. This product does all the work. If I missed a spot, I do it again....no scrubbing here!
Soap scum is what you need to remove...watch it shine with little work.
Donna