
Restriction. How about shimming your carb tops and stopping the throttle valves from fully opening? Once you get it about 3/4 opening get the bike dynoyed to show it has restricted power - sorted!!
Insurance. Difficult one !! Get third party only just now and build your discount up.
Tax. Think you can still declare the bike as not being used on a public roads but will be parked on a public thourghway so need it to be taxed. You have to apply directly to the Tax office.