I would not use an ordinary disconnect switch. I recommend that you use a toggle switch style motor rated disconnect switch. The contacts inside are designed to withstand higher make/break current and will last longer and be safer. It will look something like in the photo below which is a Hubbell item (#HBL7852D). Not 100% positive if this is the correct number but I suggest going into an electrical wholesaler and tell them you need a 2 pole, 240 volt, 50 amp motor rated disconnect switch and they will set you up. There are a number of brands that will work. A toggle switch style switch will be more compact than a knife switch. I wouldn't go to a retail store either.
The converter in an RV creates a momentary inrush current when first energized. If you plug your shore power cord in when live, you'll hear a zap and in the dark, a flash. This causes pitting of shore power cord blades and the contacts inside a receptacle, eventually leading to heat and overheating. You should always shut the pedestal breaker off before plugging in. Molded case circuit breakers like in a pedestal, are "somewhat" able to withstand the inrush current, but when it eventually fails, you just need to replace the breaker. Regular breakers aren't designed for switching duty, but that's what happens. They do make switching duty breakers but not in 30 amps and above.
JMHO
