This unit is clearly mis-labeled. I'm sure it would be fine for a house or cabin, BUT IT IS NOT RVIA CERTIFIED FOR RV USE!! It is NOT built to withstand the elements, must be vented (obvious from the top) and it's components probably are NOT built to take the rigors of bouncing down the road in a trailer or other RV. Any RV gas appliance must be sealed and isolated from the interior of the RV to not allow any LP into the interior and to operate safely and within the RVIA code. THIS UNIT IS NOT MADE TO DO THAT!!!
The ONLY certified tankless unit currently on the market is made by Precision-Temp....the RV-500. I have installed one of these in my CCD and also had one in my 40'Monaco Dynasty MoHo while I was full-timing. I have also used tankless units in my last 4 houses.
This unit is clearly a household unit, probably Chinese from the low cost (the RV-500 lists around $1000 and most of the tankless household units I've used start at $750). IMHO, your personal safety is not worth saving a few bucks! But it's YOUR hide and YOUR bucks!
Be careful out there!!!!