we did an illuminations cruise 2 weeks ago. they supply bagged snacks - chips, pretzels, smart food and soft drinks and water.
We did this for a family cruise and it was right after dinner.
There is not a lot of time for having something. Once you get in the boat, the driver takes you for a loop down to MGM then over to Illuminations where you tie up under the bridge. we were there maybe 15 minutes before Illuminations began.
Smoke may be a major factor. Depending on which way the wind is blowing, you may get alot of smoke and ash (we did!)
Once Illuminations is over, they untie and head back to the marina. All in all, including your Illuminations time, you are parked for about 3o minutes. Chocolate covered strawberries would be yummy!
Some do cakes for their cruise. Private dining can probably do whatever you would like! Let us know what you decide to do