O.K. This is probably going to go against ALL the "stuff" you've been hearing about the VW air-cooled engines but hear me out...
Volkswagen did not and would not, build an engine that would overheat in STOCK form. These engines have been around for a good long while and have been operating all over the world under some of the harshest conditions imaginable, in stock form.
The problem(s) most owners experience have more to do with poor maintenance, shoddy repair and crappy after-market parts than anything Volkswagen ever did.
One of the problems is sourcing good engine parts. Nowadays a lot of replacement parts are crap right outta the box! Another problem is finding a really good mechanic that actually knows a thing or two about these beasties. This detailed explanation is from a guy that's been doing this for a number of years;http://haysvwrepair.com/operating-temperatures/
I have had a few VW campers over the years (I'm an old fart so I've gone through one or two) and have schlepped my latest, an 82 Westfalia, out to Playa for the last 5 years. Mine does NOT have an additional oil cooler (more places to leak) Fuel injection (can't find decent parts anymore) or a paper air filter ( I have twin oil-bath air cleaners sourced from a 50's vintage bug) I DO have an oil temp gauge and a head temp gauge. They were installed by the previous owner so I just left them in. They've been checked against an IR sensor. The head temp reads about 100o hotter than the IR and the oil temp reads about 50o above the IR. And remember this; VW NEVER put gauges on any of their air-cooled engines! Why? They never needed to!
Coming up over the Sierra's fully loaded? I've never gotten into the "danger" zone on even the hottest of days. Traveling out past Reno? No problem.
Here are a couple of do's and dont's I follow these days;
I don't flog my van up to 80 MPH and hold it there all day long. It simply will not do it. Period. (Except maybe the backside of Donner Pass
I can't stay up "in the saddle" for 8-10 hours at a time anymore so I end up stopping more often for longer periods.
I maintain my van scrupulously (might not look like much but it runs real good! Stops good too!)
In short? Proper maintenance by a qualified mechanic and you shouldn't have any problems at all.