It is not just the Number Plate there is also the VIN Number and Engine Number as well
Sending the number plate back does not relinquish their ownership.
Number plates only denote the sale the place and year nothing to do with ownership.
Look up the definition of ‘vehicle’ and why do you need a ‘vehicle excise licence’ better known as Road Tax before you go on the road amongst other legal and commercial implications
If we need to remove the VIN and engine number then we could look at if there is way of getting a Manufacturer Statement of Origin (MSO) as you do when building a custom motorbike using a custom built frame and engine.
There are people on the site have no idea on all the legalese and the implications of taking of your number plates relinquishing MOT and Insurance thinking they are doing the right thing under Common Law and shouldn’t be encourage until we have a proper and foolproof system of paperwork that covers everything.
I also personally think until all matters into driving around in your own private conveyance as it is defined in common law safely and without threat of interference from the State in their various guises are currently ab inito.
Hats of to you for trying and being a test pilot maybe you could try and build you own private conveyance and place it into a Trust.