Larger engine will allow a better speed on the motorway for certain. The standard camper van engine used to give about 20 mpg if set up well.
VW pick up will sell for quite a lot of money to the VW enthusiasts. Even mini pick ups are well over 10k now.
There used to be quite a few VW campers coming in for welding at the garage but not many now so i expect owners have bought modern ones.
Most cars needing welds are at about 19 years with vans needing welds at about 14 years. Nissan pick ups suffer the most rust and terminally rotted at about 15 years.
A lot of the T4/T5s come in needing doorstep replacement but they are also over 20 years.