I haven't found any way to do that. pending a better solution (I would not even know where to start from to implement a sort of hierarchy among image devices or among multiple images of the same kind, like a basic cart for a400 and a game cart for the same system), I ended up using the same approach used for snapshots: to leave the burden on users' shoulder until some smarter dev succeeds where I've failed
like in the case of the snapname option, at least this offers a chance to users to get the desired result, even if not in the optimal way... until someone implements a better solution, I fear we will have to rely on qmc2, since he plans to implement a 'suggested option' mechanism like for snapnames in his frontend...
