I think I understand what you are doing with the masking tape, using it to fill the space between the rod and the reel seat? I do this in three sections, One at the front and back, then another in the center. This fills up the void and allows for the use of less epoxy and more support (four could be used depending on the size of the reel seat and the width of the masking tape.

If you came up with that on your own, good job!

I've heard it both ways about the spine of the bottom of a 4 piece rod. I prefer to try and find it, but I use a spining machine and it is still tough. I did just receive an Orvis 8 wt / 4 piece and they spine all the sections at the factory which I thought was nice of them. Since it is my first Orvis blank I wondered if they do that for all their blanks, nice if they do (actually I will check their work and spine just to make sure).

Have fun and enjoy your new hobby. The best part comes later when you catch a fish with a rod you built and a fly you tied (if your into that).