built or heard about the registration procedures for SSDR type in the UK.
I haven't, but the people I'd look to for useful experiences would include:-
Flylight airsports, at Sywell (Paul Dewhurst or Paul Welch would be the best people)
Reality aircraft, at Old Sarum (Terry Francis)
The BMAA (look at the TILs, then see if you can book a conversation with Ben Syson, the Chief Technical Officer)
The eGo people.
Grass Strip Aviation (Robin Morton).
Between those chaps, you've a lot of experience of making SSDR work, both importing and designing. And in all cases - building and testing.
G