Sorry to get on my soap box, but all the categorical advice like “yes, you need a sleeping bag” or “no, a liner is all you need” is good only for the person giving that advice and not for anyone else. Everyone here is trying to give good advice, of course, but whether any person needs a sleeping bag or not depends on the temperature range in which that person can sleep comfortably with or without bags or liners. That is an extremely individual physical characteristic. I “run cold”, so I always take a bag. I also take lambswool gloves — I left them home this year, and though I started in June, there were mornings when my hands were frozen. My walking buddy’s hands were fine.
I always tell people who ask — if you are the one who brings a sweater into restaurants and theaters during the summer because the AC is too cold, you likely need a sleeping bag at any time of year. If you love the icy AC, and go in wearing sleeveless shirts and shorts, you likely don’t.
Anyway, my point is that just because 45 people say that you need a bag and 35 people say that you don’t, that really doesn’t help you answer the question. And just to make it more interesting, it appears that there is a gender correlation.
https://www.glamour.com/story/theres-a-scientific-reason-women-are-always-colder-than-men