I just bought a black 2010 Surly. I'm not going to sand the original paint job. Is there any temporary waterproof paint that can go over it without damaging the original paint or clear coat, but won't come off too easily. Acrylic rubs right off too easily.
Water base paints are limited to basecoats, which need a hardened clear.
Im not going to into the details about what makes paint work, but don't bother until you have the money to get it properly painted. I have repainted one of my frames, back in the learning days, cutting corners, three times. This is neither fun nor environmentally responsible. If the factory paint is in good condition, which is more or less an indication of its quality (look for creeping rust as this indicated de-lamination of the primer to base metal), it is fine to scuff well with not finer than 400 grit, shoot base or acrylic enamel (no clear needed), and clear. Just like tuning a derailer, paint needs practice, however retuning a derailer is free and easy, re-painting sucks/ is boring.
96 gary fisher 'utopia' : 99 Softride 'Norwester'(for sale), 1972 Raleigh Twenty. Surly 1x1 converted to 1x8, 96 Turner Burner
One thing that was suggested to me. And I may try it myself. Is after re-painting the frame. See if you can get a auto body shop to put a good baked on clear coat for you. I've got my on a Surly 1x1. And if I ever got one. I'd do a custom paint job on it.