My two cents
Personally....
1. I'd use slightly thickened epoxy (mix epoxy, paint the two parts, then mix in a small amount of thickener, put that on the joint put together)
(I don't like gorilla glue, but the gorilla-glued white cedar table sitting outside for the last ten years is still holding together)
2. I'd do end grain to end grain. if you wrap the blade with fiberglass cloth anything would be OK
3. Clamping? Tape holding them together is good (for epoxy other glues different)
4. Surface prep--expose fresh wood sand the gluing surfaces, if it was really tight grained hardwood and i was using epoxy I'd rough it up with 80)
5. Unasked: I'd use some kind of spline, dowels, biscuits. The way to use a router on the end of a paddle blade is to router the blanks.

: My paddle is coming out a bit shorter than I'd like (82.5" for
: a rather wide boat) and I'd just as soon add hardwood tips
: anyway for durability.

: A few questions:

: 1. Can I add 1" of wood just glued directly on to each end? Is
: gorilla glue or titebond III workable?
: 2. Which way should the grain run on the tips?
: 3. If clamping is necessary, how do you clamp wood onto a
: rough-shaped paddle?

: Thanks