Ultraheat Tank Heater AC/DC

Looking at possibly installing an Ultraheat 40 gallon tank heater with dual elements, both AC and DC, which would allow the tank to be heated while traveling.

Sure would appreciate hearing from those who have installed this tank heater. Was the DC mode too much current draw for your tow vehicle and converter on your trailer/fifth wheel?

Would you buy this model again or buy just the model for AC only and use it when plugged into shore power?

Thanks in advance for your comments.

Mike