I've experimented with making strike indicators that way, too,
although I wasn't smart enough to think of using the latex.

But I've found that although poly has an s.g. less than water, and so
will float, it doesn't have enough excess bouyancy to float if it's
supporting a weighted nymph. Before long, it begins to submerge.

So I've been experimenting with substituting closed-cell foam for the
poly. Ugly, but works better.

vince