Great minds think alike.
I have been using a nail knot behind 2 half hitches for shock tippet for a few years now.
You can get a stronger knot if you tie the nail knot with the 2 strands formed by a bimini.
I very rarely use loop to loop connections.
These days I do not use the IGFA style of tarpon leader as I think it is unnecessary if you are not chasing world records.
My set up for tarpon is:
4 ft of 50lb mono nail knotted to the fly line. 4 ft of 30lb mono connected with a double uni knot. 2 ft of 60 - 80lb shock tippet connected with 2 half hitches in the shock and a nail knot with the 30lb.
I tie the fly on with a Rapala knot.