Project looks good, by all means eliminate the wire and use 12 strand Dyneema for the outhaul tail. Invest in some small blocks to increase the outhaul purchase. I took Bill's advice years back in my Boom Bail makeover.

As for the webbing straps, no personal experience but I saw these a few years back and thought Dyneema Climbing Slings might be an inexpensive solution. Unclear how class rules would apply.