Answer: We aren’t sure if you are asking about adapting a 50-amp power source to your 30-amp RV, or vice versa. Or perhaps you are considering converting your entire RV electrical system from 30-amp to 50-amp.
If you are thinking of converting your entire RV from 30-amp to 50-amp, first we suggest you contact the manufacturer to assess the impact to any remaining warranties on the RV. If we had to guess, we would think it could be costly.
From what we have read, while such a conversion may not be an impossible task, you really need to know what you are doing. Considerations include complexity of the needed changes to wiring, transfer switch, breaker panel and generator; impact to weight limitations of the RV and cost. Also note that some RV parks offer only a limited number of campsites with 50-amp service (or none at all).
You might want to consider taking the RV to a qualified RV service facility. We did come across a website of an RVer who has done such a conversion. We can’t endorse their guidance one way or the other, but you can see what they did here – http://www.bobhatch.com/electricStuff/30to50amp.htm