I have sleeping bags that have been stored in their stuffsacks for decades. And I still get over toasty when sleeping in them. There may be some degradation in loft, but shake the thing to fluff it up and put on a pair of dry socks before bed and the difference in compressed vs. uncompressed storage is probably pretty minimal. I am not talking about a compression stuff sack for storage. Just a regular stuffsack, or a compression sack that has the straps loose so it goes to its maximum size.

If I had a $500 down bag I might be more careful. But I don't. All my bags are $150 max, and most are significantly cheaper than that.

Take a flannel sheet, sew it into a bag, and use that as a sleeping bag liner. That will probably add more warm than storing the sleeping bag compressed would ever take away.