I had a request for a mouse fly that i tie and have had some luck with this year. Here it is. I apologize for the crappy pictures.
Fox squirrel zonker strip
Tie in chenille for the tail. I burn the tip and apply some zap-a-gap right where it meets the hook so that the tail is stiff for about 1/4". I think it helps prevent fouling.
Cut two pieces of foam. I usually make the top one a little wider than the bottom
Tie the lighter one on the bottom and the darker on the top. After that, tie in the squirrel zonker.
Tie in a rubber leg on either side.
I usually put some SHAN on the shank and then wrap the zonker up to the eye and tie it in.
Split the hair on the bottom of the shank, pull the foam to the eye, and tie it in. I put some superglue on the foam to glue it to the shank of the hook. I forgot to take a picture after the foam is tied in
Flip the fly over and do the same to the top.
Tie in some more rubber legs at the front tie in spot and your done.
I also tie one that i double the top foam and dont put a bottom foam. Both work, just depends on how im feeling when im tying.
Hope it works for you.