Hair dryers and hot plates also have a high steady power demand. A/C's are still the best and easiest to use. If your A/C has heat strips bonus time when the air temps are cooler.
Just do a little math a head of time to source stuff to create a large enough load. A little harder when plugging stuff in to get into high wattage territory. If you're running multiple items to create a load just be sure to use multiple circuits so you don't pop a coach circuit breaker. 15 Amps @ 120 VAC (a common line breaker in a coach) is only 1800 watts and to get to 7000 watts you'll need to demand almost 30 amps of electricity. Watts = Volts * Amps.