Buy the 50 amp, plug your 30 to 50 dog bone adapter (if by chance you have the hockey puk adapters, throw them as far as you can, they're a fire hazard) into the pedestal then the surge protector into the adapter then 50 amp as usual from there, the only possible damage would be to your dog bone adapter, have done this numerous times & works great.. I've had the portable for almost 12 years, the last 10 it's been in use every day all across the country & has never walked off yet. The hard wired is nice, but if you ever plan to trade rvs you'll have to buy it again, I'm on the 4th rv with the same protector, well actually the 2nd, the first one fried at a park, but no damage to my rv, replaced under warranty.
The moral is; if own a rv, DON'T LEAVE HOME WITHOUT ONE!!!
Danny & Linda
Sold our '13 Thor Redwood 36 FB
Currently RV & truckless