Hi Martin,
On the boat I just bought, there is both the sloper back and the full bimini cover. The poles stay attached all the time on this boat and the sloper cover is modified to wrap around the bimini poles. I can send you photos if you want. I think you could likely get a local shop to make mods to your sloper cover. This is a nice setup since you can quickly but the sloper cover on to keep the rain out without having to remove the bimini poles and store them somewhere.
Glen