Taping it off to paint is fine as long as you can reach all the parts you need to with the paint. Just envision how you want it to end up and act accordingly. My mind's-eye-view of your situation is that there is no need to remove the top.
The cab must also have weathered, porous paint for mildew to take hold. By all means, if the paint isn't weathered to rusting metal, a coat of wax should solve the problem. I think you know better than letting the finish go more than 6 months without a coat of Turtle Wax - admit it, you just got lazy! Iv'e tried all the fancy pure carnuba waxes, polymers, silicones, etc., and find that they aren't any better than good old liquid Turtle Wax. Since it lasts at least 6 months and you should be waxing that often anyway, why pay $$$$ more for essentially the same thing? I like the idea of the colored waxes that don't show the tell-tale white residue but haven't tried them yet.
If you lived in a decent state like California, you wouldn't even know what mildew is!
[ September 06, 2002: Message edited by: firstname.lastname@example.org ]</p>