That seems to be a problem with 30 amp outlets! There are only 3 prongs, and you have an adaptor and heavy 50 amp cord plugged in to the outlet! Over time the prongs in the receptacle get loose causing a poor connection, this cause heat build up, and you end up burning the plug/receptacle! Proper breakers are designed to handle only 80% rating for continuous use, which would be around 24 amps continuous draw. I do not think your issue is the breaker as much as the receptacle. A permanent fix would be to replace everything and end up with a 50 amp service. No adaptor required, the 4 prongs are better able to support the weight, you should take precautions to keep as much weight off the receptacle as possible to prolong its useful life, and your rig will be happy using all the power it was designed to use!
