Painter's Tape won't do anything. Fiberglass becomes rock hard when it is covered in cured resin, which is why it's used (it's also used in boat hulls, fyi), and bondo both hardens and is easy to sand and detail. There are plenty of ways to make fiberglassing easier. As well, you're not supposed to fiberglass the outside unless you want it to have no detail at all.
What I do is resin the outside a few times, give the inside a single coat of resin, use spray on adhesive once the inside is cured, then just slap in the fiberglass without time constraints or the fumes. Then, all I have to do is give it another coat of resin. More time consuming, but more simple.
As for smoothing the outside, you'll either wanted bondo or rondo. None of these improvised materials ever end up working, from what I've seen.