Marc, first let me say very nice job on the extender. Probably one of the best home-made ones I have seen.
However, the problem I see is that it is based on the noose type extenders which are notoriously uncomfortable and dangerous.
You may want to check out Monkeybar's vac-extender head piece. It may work with your extender and would replace the noose head piece.
I don't own one but many guys praise them. They are supposedly very comfortable to wear for hours.
Here is a link to his site.
Autoextender Penis Enlargement Device If you are interested, I would send him photos of yours to make sure it would work.