Registering an out-of-state purchace

I believe most Oregon DMV offices are open, albeit with COVID restrictions....reservations usually required. Most registration issues can be done on-line. You might take a good look at the Oregon DMV website. To remain legal you do need to get hour RV to Oregon before the Washington permit expires. Once in Oregon I suspect things to be a bit more forgiving if you don't get registered quickly......call or contact them Their customer is pretty good.