Sunken 'float'

The klinkhammer photo reminded me of Brook's 'tied in the round' theory.

This would probably be more on topic over at the tying list but

Does anybody have thoughts and ideas on ways to make sure that two tone
nymph patterns actually 'float' near the bottom top side up?

Nymph patterns with backstraps of PT ( or other) and bellies of fur or other
look great in the vise, but tumbling in the currents?

Related query: good ways to build 'wide bodied' nymphs .... rhithrogena
for instance are very wide and thin, round is not an accurate body shape.
I'm think that one of you bright lads or ladies might have practical ideas
that would make it easy to both improve the shape of clinger/crawler nymph
ties and stabilize their 'float' right side up at the same time?


Sandy? Littleton? other sharp tacks out there ?