Ideal Concert Lenght - Upcoming Event

Hey guys I have a Question about an upcoming Event I am planning with my band. It’s the third time this event will take place a our town hall , we’ve been organizing a Three Band lineup every year with free entry where all the Proceeds go to local charity , it’s all local rock and metal cover bands. Doors 7:30 PM and opener at 8 PM , my band usually gets the headline spot and here’s the thing : I think our setlist is way too long for what we do , it’s just a cover band with very little to none show or anything , pretty bare bones just some dudes making music anywhere from Green Day to Slayer and in between but my mates who have been in the band almost ten years have collected such a big bag catalogue of songs of which they want to play almost every song that the set is somewhere between 3 to 4 hours which I think is just way too much for a band like like us. I keep trying to make it shorter where I can but for every song we kick out another one gets added like "we haven’t played that in a while let’s just add that to list". I’m noticing how the crowd gets smaller and smaller every half hour and I can’t even blame them because there’s just not enough happening on stage to keep people hooked - don’t get me wrong I don’t wanna do some sort of big show act I just think we should accept what we are. The other bands play until 10:30/11:00 PM then it’s our turn which is already kinda late to me - I think the whole event should start at least an hour earlier and we should cut down our set to a max of 1 1/2 play time which adds up to about 2 hours after all the tuning , talking and so on. Please help me on this one - should I tell em like this or am I off ?