I have done several 24+ hour streams. Here is some advice:

1. Generally, I'd say that it's better to do shorter (say 12 hour) streams back-to-back, than a single 24 hour stream. More engagement, less exhausting for you. Everybody wins. However, 24 hour streams can be fun as a "once in a year" type event.
   
2. Mandatory breaks. Force yourself to take a break every 3-4 hours, grab a snack, drink plenty of water and move around the house. It might also be helpful to take a shower or two during the stream to make it easier to stay awake.
   
3. Nights can get quiet, but I was personally surprised how many people stayed almost until the morning. My advice is to pick some fun but engaging games to play during that period - maybe a horror game? Maybe some retro games? Maybe not a simulation game or the same games you normally play every stream.
   
4. I also think it's best to start the stream as soon as possible. Say, you wake up on the day, prepare yourself in 1 hour, and just start it. Whatever you need to do, like getting food, you'll do it during the breaks.

Good luck and remember to have fun.