Tap into my 30 amp Dryer outlet for an RV outlet???

Perhaps you need to check your dryer breaker to see if the one in your panel is 30 double pole, and you have another individual breaker that feeds power to your gas dryer. The gas dryer requires a dedicated circuit, but it is 120 volts and should have a 15 or 20 amp single breaker.

In either case, the answer is no, you should not tap into that circuit.