The inside tape is protected from abrasion and serves to strengthen the joint from the inside. If you put it on the outside and you grind it off on a rock, your bow/stern ends will not have any structural intergrity aside from the glue holding the joints together. There shouldn't be a problem if you overlap the tapes by a half foot or so (not much of an additional weight issue) and add the extra half a foot you require. The external aspect of the bow/stern usually gets an extra dose of glass for added strength. I have 3 external layers made from cutting strips of 6-oz glass and the one tape on the inner seam.

That's my $0.02, hope it helps.

Robert N Pruden