If I had to guess, it be in the $1000.00 range. I've often considered it as I camp in the washes. I've covered with every over the counter cover they offer. It just doesn't work in the rain with wind. I like my car and care for it like it's candy and I'm not alone. I transport in a fifth wheel and store at Glamis so I'm not dealing with what your looking to do. But if I was, towing open and had weather up against me, I'd throw the fitted custom cover on and sit it out till the rain stopped.
Most will say don't pressure wash or use a hose to wash your car, just wipe and blow it out. Then in another comment they say tow in the rain. I don't get it.
You can be prepared if you choose to be. Having a good cover isn't a bad choice.
Just my opinion.
:cheers: