Yes, with a 50/30 dog bone you can plug your 30 amp cord into a 50 amp outlet
BUT you will only be able to use 30 amps becouse you have a 30 amp breaker in your RV. FYI, 50 amps is 240 volts. 30 amps is 120 volts. The dog bone only gives you 120 volts.
Your RV breaker is still gonna trip. You must learn energy managment.