harness's 'R US?
I forget where youse guys are...the Kootenay's?
I bought a roll of automotive seatbelt webbing at Surplus Herby's, and had the shoe repair guy next door stitch up a harness for our previous a/c. .....it seemed really tight and sturdy to my eye.
Maybe not a lot of stitchers around anymore, but don't forget the industrial supply houses ( Acklands?) that might deal with fall-protection harnesses, (although they usually get tossed), or the stock-car/racing shops.
Outfits that do big tarps for trucking or awnings for the sign business may also have industrial stitching machines, but that's getting a bit out of the seat belt field.
Then there's a lot of guys that do leather harness & saddles, or gear for the motorcycle industry.
good luck eh?