I'm also probably not the best to give advice on this since I'm 18 years away from knowing what 54 feels like, but I'll toss an idea out for you.
If I were limited to lifting on those days I would be running a full body program, lifting on Tuesday, Thursday and Sunday. If one of the days is particularly hard, do it on Thursday. That gives you a full day of rest between each lifting day, with two between Thursday and Sunday. If you're dead-set on doing something on Wednesday, do active recovery and/or conditioning.
Simple squat/push/pull 3 days/week worked great for me.