Yeah, there's not much you can do about that. When it's super hot and we need to BW I only do back carries since it doesn't affect me as much (well, last summer when front carries were an option). I did a lot of stroller time for evening walks. BWing just isn't the most practical for outside in 100* temps with high humidity! It was 100* and super humid today and I couldn't manage BWing DS across a parking lot - DH had to do it! lol
And linen does very well once broken in well! Sit on it (seriously lol), play with it, etc and it should get easier to work with in the rings. Just keep practicing. Sometimes smaller rings makes this harder.
Start with the rings on top of your shoulder so when they work their way down from adjusting they'll be right in the perfect place! When you take a kid out, you shouldn't let out much at all, just barely enough to lift the kid up and then out. This way there's little adjusting for next time!