Paul,
A late reply as I've only just joined TM.
I have fitted overiders to the rear of my 95 plus 8. They are the type fitted to the frog eye sprite and the advantage is that they don't have any cut outs to accommodate a bumper. I think they were called bumperettes at the time. Bought them from Cape, the Austin Healey people.
I had to make a couple of brackets/plates to fit inside the overiders and could then use the original bumper brackets fitted to the car. I didnt fit a luggage rack but don't see a problem in doing so.
Bob.