I am 60, retired 12 years, have been 100% in stocks for decades, and never have trouble finding stocks to invest in that I consider undervalued.
That said, when I was 43 I paid off my mortgage early to celebrate reaching an important financial milestone. Although I would have come out ahead investing that money also, the joy of being debt-free outweighed it for me. Sometimes, you just have to splurge.
I'm also in your camp. Also 60 years old. I have been in 100% stocks for about 15 years now and have done well with it. But, unlike you, I do have a mortgage currently and have posted earlier on these pages that I'm in no hurry to pay off the mortgage. I don't see the need to own 100% of our home, now or until we die. We have not had luck with our home ownership (always lost money). Very comfortable letting the bank own most of our house while we live in it. Barring some extreme event, plan to be 100% in stocks. Even if we do modestly lesser with our portfolio, expect the mortgage to be a smaller piece of our net worth, especially if one of us lives a long time. We hope