I'm replying here mostly because no one else has and I wanted you to know your
message is out here!
I googled high altitude RV appliance use and found a thread on RV net here-
RV.Net Open Roads Forum: Affects of Altitude and Temperature on Propane Use
Beyond what they say there I can only advise calling the tech line for your appliance.
We camped at the north rim of the Grand Canyon for a week and had no problems.
Actually we spent a month in Colorado and Utah with many days in the high country
and had no issues except my little Weber charcoal grill wouldn't burn with the lid
Also camped at Leadville CO which is over 10,000 a few years back and don't
remember any problems with hot water or refer then either.
I suggest just because your previous trailer had problems don't assume your
current one will.
I think it might be OK as is!
Good Luck and Happy Camping!