I agree with the majority.
Mostly at WDW with extended family we just used hot water and soap.
One trip -t o have coffee- we had a car and bought a coffee maker (to have coffee). There's a
Walmart on 192, and coffee makers aren't expensive. We gave it away before we left (glass pot).
You could also try a small hot pot, or the microwave bags as suggested.
If you bring enough supplies to last at least half your trip, that would help. Walking back and forth to the food court is time consuming.
It is also worth noting that many kid meals come with an option for applesauce. If we've gone to WDW with children six months and up, we just bought kid meals and asked for double apple sauce (someone else ate the rest). Also, it is pretty easy to mash up a host of foods for an infant over six months: rice and bananas come to mind. Babies survived for ages before food processors came about. They also survive now in plenty of places that lack electricity. one infant food not readily at WDW is Cheerios. You can often find tiny boxes of Cheerios in stores. Ziploc bags are also great! (snack size up to the two gallon ones, or the giant ones are too big for travel.)
Another trick we employed: babies can use straws, in a pinch. Dip the straw in the drink, and plug the top end to create a vacuum. Slowly release. And almost any baby above six month can use a straw, just burp them. They already know how to suck.
Napkins can be used as burp clothes.