Originally Posted by Zephod_beeblebrox2
The main cable is 6-2 so plenty room for expansion as it'll carry 55 amps.
We could have helped you out on this one.
While your installed cable will, in fact, let you do what you say (by tapping one hot leg of a 50 amp RV pedestal plug) it will only buy you an additional 20 amps over a 30 amp system. You could have spent just a little more and installed 6/3 cable, wired the panel and outside receptacle for the full 50 amp two phase service (two 120v hot legs) bought/built a proper 50 amp, 4 conductor extension cord, then picked up one 50 amp to 30 amp adapter and one 50 amp to 15 amp adapter. Then you would be set to take advantage of full 50 amp power (100 amps total), and also 30 amp or 15 amp power with the simple swap of an adapter. As you've built it, you'd have to replace everything upstream of the breaker box to get full 50 amp power.