pennrver wrote:
...Any thoughts on barn dimensions? ...
Build the absolute largest you can afford. If there parts of the building that can be deferred in order to free up budget for size, then do it. For example, if you are going to finish off the interior with sheetrock, spend that money on square footage now. Come back later to finish the interior.
Also, put in as much utility stuff as you can now. Maximize the electrical panel (200amp), even if you don't anticipate needing it. You might in the future. And it will add value to a potential buyer if/when you ever sell it.
The smartest thing I did when building my shop was put 2" PVC under the concrete floor to the other sides of the shop from where the electrical panel is located. I had no plans to use the conduit, but I installed it anyway. A few years later as I did things like add a workbench, it was very easy to simply pull wires through under the floor.
Only other suggestion is to triple check the door height. My neighbor bought a new RV last year. Went to pull it in his shop where the old RV used to sit, and it was too tall by a few inches. There has been a recent trend to make RV's more narrow & taller than a few years ago. Make for darn sure the door height will clear your RV with room to spare.
HTH!
-Eric