RE:Fly falling apart, what can I use/do?
Without seeing it, I can suggest a couple things:
a) you can go for a slightly thinner thread and use more wraps, crisscrossing and wrapping fore and aft to keep eyes straight. A couple drops of zap-a-gap (a common hobby store superglue) will turn it into steel if you have enough of a thread base.
b) coat with epoxy being careful not to load it up too thick to throw off the profile and balance (aesthetic) of the sand eel fly.
c) use quality eyes, I use "real eyes" because they are steel (vs. soft lead) and have a deep vee in the middle. They also have recessed eye sockets to allow sticker eyes (match the diameter w/ clearance) to be applied without glue.
d) watch the back cast, most eyes are lost on the back cast as opposed to the bottom - unless it's a rocky bottom (as opposed to sand or gravel).
e) use a bendback hook instead of weighted eyes to tie the fly - it'll ride point up if you tie in the material correctly. Put more material on the side you want to ride up, especially if it's bucktail or other hollow natural hair. You will need the sinking line to get it down but it will glide on the bottom without snagging.