effiency of generator and house A/C vs dash A/C

Are you talking about overheating the engine while using he engine/cab air conditioner? That shouldn't be an issue.
But, it's a good reason to run the generator and house A/C if it is a concern.

I don't think it's any more or less efficient running the generator/house air. The difference would be minimal either way.
Don't worry about the fuel use. Fire up the generator and be comfortable.

You will not hurt the generator by running it when you are driving.