A.C.
I don't think you are asking too much. And don't consider your taking her away from what she's doing an interruption... it's a rule. Tell her she can have no more than 2 or 3 different toys out at a time and when she moves on to something new she needs to put away the toys first. If she's leaving lights on or leaving toys out, it is reasonable for you to nicely remind her that she forgot and have her take care of it immediately. You will not be teaching her to interrupt, you'll be holding her accountable for your house rules (make sure you make it a rule). When I notice my kids playing in a new part of the house I sometimes nicely remind them by saying, "Did you remember to put away your other toys? Are the lights off in the bathroom?, etc."
If you continue to pick up after her she'll learn that you'll come along and take care of things she should be taking care of. Can you imagine that as the years go on? Fix it now while it's just toys and lights.
Good luck!