I tied something real similar a couple years back for a fly swap. Great looking flies!

Sometimes, the mylar tubing doesn't want to turn inside out after tying it onto the hook. I figured out that the eraser end of a pencil would fit nicely into the size mylar tubing I was using and would make it a LOT easier to push the mylar onto the fly after tying in the head.

I usually leave the mylar tubing long after tying off near the bend of the hook hook. Then use the bodkin to unweave the tubing that's behind the tie-off point. It gives the tail more flash (just an alternative to trimming it short and leaving the tail as only marabou).

I worried that the hollow body would hold too much air and lay on its side in the water. I figured next time I tie some, I'll put a little weight on the top of the hook to make them ride clouser-style.

I was thinking of tying some small ones on 3x hooks and coloring a big orange spot under the front (to look like a alevin). I have a couple small clousers with a blob of orange on them to look like alevins but it might be just as easy to adapt this pattern (it's spawning season so alevins seem like a good match-the-hatch pattern).

Thanks for sharing your flies!