I think you should have a conversation with your wife and draw some mutually agreed upon lines in the sand here. I get what you're saying - the purpose of separation is to figure out if the two of you are meant to be apart. Your current arrangement does not support that model whatsoever as she's getting the convenience of a Mr. Fixit husband without having to live with him and be his wife.
When you have the conversation, be careful about how you phrase things. Let her know that you don't mind doing these things for her - you actually love being her husband - but you're afraid that this arrangement might become a "new normal" indefinitely relegating your marriage to a state of limbo. This is a time when the two of you spend alone time contemplating whether or not you will remain in this marriage. A time to experience what life is like without the other in it as a partner. If you, NoGlam, already KNOW you want the marriage and are willing to do whatever it takes to save it, tell her that and also tell her that you'd like to move back home to get started on the hard work of R. The "hard work" does not entail stopping at the store for toilet paper and swapping out the propane tank on the grill.
I can definitely see your dilemma here and I don't blame you for being concerned. This can be solved with some open, honest, and compassionate communication.