Which webbing/strapping ?

http://seattlefabrics.com/webbing.html

a not stretchable nylon would be acceptable…from where ?

I bought polypropylene on SF’s recommend . Polypro does not glue but then does not stretch.
Polypro sewn to the PVC patch then glued to the vinyl hull..the thread is now glued down. But yes it would be best to glue the strap into the patching.

40oz ! yes this is rational if not commercial. The expert suggests hi denier with quality stranding. Are heavier weights inversely proportional to denier ? This sounds commercial.

http://www.nrs.com/category/2988/rafting/pvc-pu-adhesivessolvents

supplies LA 4123. 4123 may be in your can under another name.
From cost, I assume H-66 is Less 4123.

NRS has the fabric under RAFTING>repair>n

I used MEK ( in a strong breeze) for NRS patching for Bills Bags onto a Rendezvous vinyl using Vyna Bond. Vyna gives way to 4123 and Loctite
http://www.loctiteproducts.com/p/cntct_vnylpl/overview/Loctite-Vinyl,-Fabric-&-Plastic-Flexible-Adhesive.htm

The Walmart Loctite is less half the holding of Vyna…but I did not have MEK on hand. Reports on using MEK as a surface on vinyl sheet before Loctite vinyl adhesive ?

NRS suggests alcohol before MEK with Clifton 4123