As a fellow Texan, Licensed in Texas does NOT mean anything when involving Electricians. Just ask him a simple question.
Is a 50 amp RV service 220 volts? If he answers YES, then do not hire him. But it is NOT 220 like most people think of 220 (dryer or welder plug)
If he answers NO, then ask him a follow up question. What is the TOTAL amps on a 50 amp RV service. (not a trick question) The Answer is 100 amps. If he fails this question, do not hire him.
I have repaired scores of RV's that have been burnt out by incorrectly wired 50 AND 30 amp RV service by Licensed Electricians. Doug