Check with your insurers that they are happy wit that plan. Some are not. Also check with the farm in case the famer asks to be able to move the van for his own farming reasons. He may store it in one location for a few months and the need to get access.
They obviously make a van harder to steal but not impossible. If thieves want it, they will get it.
The one downside is if you wish to move the van in a hurry, then it is difficult. You also have to store the main wheels at home and that can be awkward as they are bulky.