This is possible, but is not an engineering project!
There are two options:
(a) Form your own insurance company:
Firstly find enough people with ££££££ to invest so that there is enough to cover all potential claims (and Public Liability i.e. 3rd party claims can run into millions).
Next, agree a set of criteria so that similar risks can be pooled together for homogenous exposure. NB this must include all kinds of modifications.
Work out expected loss ratios and profit margins (believe it or not but investors might like to see a little bit of growth on their investment!,) and once this is done calculate premiums!
Market it, but let's face it there is a lot of competition out there already!
Or (b)
find enough interested owners of similar vehicles that have been modified to within agreed parameters that you can persuade an existing insurer to take the risk on-board.
Alas both are unlikely!!