I mean this in the nicest way, but sometimes you're hard to reason with. If I suggest that you change the tire out now, you say "yeah but I like riding outside with my good tires." If I suggest that you take your chances, you say "yeay but I'm afraid I'll ruin my good tire." IMO, you likely can't have it both ways. If it were me, I'd accept the lesser of these two evils and change out the tire now. That's arguably the most budget-minded option you have before you, assuming a dedicated trainer tire is cheaper than one of your premium tires. If you do change out the tire now and get a spectactular day of weather that allows you to do a long ride, you could always just take a few minutes and change the tire back out to your good tire.