I'm sure that it's an embarassing and frustrating issue that involve multiple sides. I can spout off many nasty one-liners about the stop-sale but they wouldn't be helpful.
So, sit tight and revel in the knowledge that you're not alone in the misery.
There's a possibility that a set of wheel adaptors would make your OZ wheels fit on the Supra. The possibility is even greater because it uses lug bolts meaning the adaptors could be made thinner.
Standard coverage (partial hood, partial fenders, full bumper) takes a maximum of one day to install. Additional items like headlights, exterior door handle pockets, A-pillars, and mirror caps could be added without adding significant installation time.
The two-week quoted time is likely due to...
It's the nature of such a vehicle with a projection of lower production number. If you needed a car by August and unwilling to pay a mark-up, a Supra would unlikely be a good choice. In my local area and at this point, getting in line for a LE at MSRP is impossible.
Toyota Accessories website doesn't show mudguards for the 90-series. A reputable clear bra installer can cover necessary panels (rockers, leading surfaces of quarter panels, etc ) to prevent damage from road debris. Clear bra is also much more effective than mudguards.