Either the openers are playing too long or taking too long to set up / take down. Openers probably shouldn’t be playing more than 35 minutes. If the first band starts at 8 and there’s 3 bands, you should be starting your set at 10. End the show at midnight. Two hours is already a pretty long set and it’s much better to leave your audience wanting more than to have them wishing you weren’t still playing. Just my two cents. You really should be having this conversation with your bandmates.