My understanding of the rules are that it is declared MOT exempt or it has to be MOT'd annually as normal. If it is MOT'd this gets logged at the DVLA as normal and then if it is not done when due the following year then that becomes an offence as it is not subject to the exemption. To do what you suggest would require you to re declare it MOT exempt every other year. Surely better to just get it inspected by a tester unofficially if they will and keep a record of this and also invoices/ proof of any work required being done.
I don't think that's right. You can't declare the car to be MOT exempt. Filling in the V112 form makes no difference because it is not logged anywhere, so DVLA or whoever it is won't have any record of the MOT exemption anyway. When retaxing, they don't ask if it is MOT exempt, just if it has been "Substantially Altered". My understanding is that they assume all vehicles that are classed as "Historic" will automatically be MOT exempt unless they are highly modified. The fact that I have had it tested doesn't alter that fact. Yes, the MOT has been logged on the vehicle's record, but that doesn't alter the fact that it is "Historic" and therefore automatically MOT exempt.
I don't honestly know what the point of the V112 form is. The post office don't log it, and it doesn't get sent to the DVLA. It is just a piece of paper with my writing on it and I can't believe it has any function in law. I could easily have knocked it up myself on the computer.
Anyway, if I'm wrong I will find out next year