Where is the best location to mount the spin pole base(other
than the front of the boat). I am putting a spin on my 5.2 & have been told the ideal location is with a clamp on the
dolphin striker, have also seen on Hobies where it mounts on the front cross member. This is a home made assembly, I found a two piece carbon windsurfer pole which is a little over 13 feet, I'll cut it to 12 ft mount my hardwere, etc.
Any ideas, concerns. pics of other mounts.

I used the front beam on my H-20 (RIP) with good results. I mounted an eyestrap with the enclosed insert horizontally on the beam and used a long cleavis pin to secure it.

Ferrule eye strap, available at West Marine.

On my 5.2 rig I bought the pin that the Inter boats use and just mounted it to the front beam,

check out my write up on the 5.2 spin rig I just finished. there are some good pictures and info.

Mine has a U shaped piece of aluminium riveted to the front beam with a horizontal pin, parallel to the beam, going through the pole to hold it in place.

Capricorn

Use a rubber universal joint for attaching the pole to the beam...inexpensive...piece of cake to attach.