Considering the fact that most guests hardly read anything at all I would say your late check out message is a bit wordy. I know exactly what you are talking about and I can barely comprehend it.
And it doesn’t even cover early check ins!
Believe me, clueless guests do not care about your scheduling problems.
The place I rent out is in a drive to destination at the USA Southeast coast beach. I get guests from up to about 1000 miles (or more) but usually from 500 miles or less.
I do get guests who want to arrive early or depart later.
Check in 3:00PM, check out 10:00AM. No early check in or late check out without written permission.
See? Two sentences and if they are interested we take it from there.
If they are interested I message them: Guaranteed early arrival or late departure, if available, incurs $100 fee." (or whatever fee depending on the season) If they want to take a chance that it’s available, I’ll give it to them but that is on them, and it has to be discussed beforehand.
If they don’t opt in and are not out on time and I have a turnover situation, I am on the phone telling them to pack up and get out and my cleaners are told to hang out in the parking area and then barge in around 10:30 or 11 and get started. (This has only happened once.)
Anyway, keep it short and sweet and then do what needs to be done.