I just remember something that may help. It may be a little weird, but go with it for a minute.
Our previous tenor player on my ship introduced me to this because we had to sometimes play 5+ hours a day + practicing and it made a huge difference with embouchure fatigue specifically lower lip fatigue.
I can't remember what it's called though
... What I do know is it is a light pink, waxy, thin-ish material in the shape of the curve of your teeth. I included a pic of how it looks out of the box and how it looks when you are done (forgive my fuzzy green blanket LOL)
1. Cut wax into 3 equal pieces.
2. Take one piece of wax and slightly "pre-fold" it in the middle a little to get it started.
3. Place wax over bottom teeth
4. Press down firmly to mold the wax to your bottom teeth
---- start by pressing down the very middle section behind your teeth
---- work out to the left in right - behind your teeth
---- with one hand hold the wax firmly against the back of your teeth ... with the other, press down the front half the wax - starting again in the middle
5. Once you are finished, play for a little bit to let the wax warm up and settle (or do a full practice session or rehearsal is also fine).
6. After you play, take out the piece of wax and store it safely - aka in way that will make sure it won't get squished.
---- when you take it out it will be warm and very flexible, but it will harden as soon as it dries/cools down.
7. Next time you play, use this piece again. It should just fit in like a mouth-guard or a retainer or something similar. Again it will become soft.
8. Use until you feel it's time for a new one. (It's one of those it last longer or shorter based on how much you play). As long as it's not broken or gross, use away!
This worked great on saxophone for me and it might help you either as you build up your stamina again or generally.
)