I did the same thing with a garden tractor a few years back so I could drive it lawfully across a road onto public land where I used it to cut grass etc.
The dvla forms were pretty straightforward and their main concern was the age of the vehicle. I ended up with a letter from the company who bought out the company who used to make this tractor saying it looked to be a 1979 model. Hey presto I got a V5 and a number plate.
I sorted out insurance, it didn’t need tax or an MOT so I was fully road legal.
First time out I sneaked up on a police car and asked them to check out my tractor.
They were amazed that it came back fully documented and congratulated me.
But then they said “we don’t really give a toss, you could have been driving the wrong way down the M1 naked on this thing and we wouldn’t have bothered stopping you. We don’t have time for this kind of Sh1t”
Talk about a lot of effort for nothing.