A 30 amp inverter with a high peak start can run >$2000. You'd need something like 300 amps at 12 volts to run it. I don't think you can get an alternator that big so you'd need the biggest one you can get, and many many batteries so the AC did not cook them with the high draw - maybe 10 or more? Even then you could not run all day. Plus that's a lot of weight, space and maintenance. So say maybe $1000 in batteries plus $1000 to get them mounted and all wired in? Plus some kind of charge distribution system. Plus the price for a heavy duty alternator installed.
You might do better to get a non RV genset, and plug into it with your shore cord. Some people have done this successfully driving down the road. 3000 watts will run most RV AC's. 2000 will run some. I do not know all the pros and cons of this approach, only that it has been used by some.
