low(er) wattage hot water heating elements?

The standard hot water heating element seems to be 1500W for small tanks. Does anyone know of lower wattage ones being available? Our trailer only has a 30 amp connection and I find in the hot summer with the AC on and the hot water cycling (and any other small loads) we trip the main sometimes. It's annoying and I am sure a smaller element would keep up to the modest demands just fine.

Not really a big deal, I am just curious.