Hi John,
Nice flies. The first is a smasher
Tapered but slim bodies are fairly easy to come by with a little practice. You have options, three of which are:
Build the taper with thread wraps.
Build the taper with dubbing.
Build the taper with underwire / lead
Ofcourse you should use these methods together to help form the smooth and gradual taper.
For example, on the back of the shrimp, you need a bulk of lead to give you the shape and then taper this gently with the dubbing and thread to ensure that you get the slim profile required:
Limiting the amount of materials you tie in at the base of the fly / bend of the hook will also help a huge amount.
Hope that helps. Sorry if I'm telling you stuff you already know.
Cheers,