Electrical power question

[Preston Smith <prbasmith@gmail.com>]

Good Day Shop Talkers!

I have a 5.5 kw Onan generator on my motorhome which makes its output 
available for use via a 20 amp and 30 amp circuit.

Is there a means of ganging these two outputs together so that I can 
feed a single nominal 50 amp circuit to an authorized switch panel which 
would power  selective circuits when the commercial power is interrupted?

Thanks

Preston