Stewart, as it's a race only car, not for road use, stamp your own. It shouldn't have to conform to DVLA specs - how would you get on for a scratch built dragster that had never been a car? Something like SRR2016001 should be fine. SRR for Stew Rat Racing, 2016 is the year and 001 because it's your first racecar!
I had wondered about that - sounds like a plan as that amount of peace of mind is worth having, especially for 90 quid.
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