Yes. Look at Atwood knockoffs or a Precision Temp 550 series.
I have a Precision Temp 550 and love it. It's slightly taller than the 6 gallon Atwood but I was able to easily fit it into my AS in a couple hours. Recommended if your family loves hot long showers....
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'The Silver HamShack' (2007 International 22FB CCD 75th Aniversary model)
Multiple Yaesu Radios inside and many antennae sprouting from roof, ProPride hitch
2012 shortbed crewcab 4x4 Toyota Taco TV with more antennae on it