We have to drive from Tampa to Charlotte this weekend.
We can get food from a drive thru, but where can we use the restroom?
Are rest areas open? Are restrooms open at McDonald's or other fast food places?
We will be driving thru North Florida, West Georgia and South Carolina

Gas stations

2nd tree to the left....

We just made a similar trip and found most of the Rest Stops on the Interstates were open so you can use the restrooms there. Also, we had no problem using restrooms at gas stations - they were available everywhere we stopped. Never tried using a restroom at any of the fast food places where we got take-out so can't comment on availability of restrooms at those locations but I suspect some places will have them available and others may not.

No. Restroom will not be open at fast food restaurants, unless they open up to inside dining soon.

Gas stations.

I just drove 2000 miles from So Cal to Chicago. Do not count on rest areas being open as many were closed along the route. Rely on gas stations.

Also supermarkets are open, some will have restrooms.

A jug in the car.

A friend and I were laughing yesterday about a Folger's can!

Starrs, that would work! Gas station bathrooms are normally bad unless a truck stop.

Once a co worker was stuck in traffic for hours and decided to use her thermos for relief. Sadly, she used the cup from the thermos. Needless to say, there was a bit of "splash back". As a joke I gave her a funnel and a washed mayonnaise jar. Then I thought about it a bit and decided it was a good idea. Since then I have a bag with a funnel and mayo jar in the back seat of my car.

TruckStopGuide.com

Pilot stations (also Flying J) have good restrooms and good "stores". As Macross pointed out, they have truck stop services in the back and car customers in the front parking lot. Quik Trip also are great options.

A friend keeps a bag of kitty litter in her trunk in the case of getting stuck in a traffic backup!

My experience has been that rest stops are open, fast food restaurant restrooms are NOT available and even some gas stations were not letting customers use their restrooms. It's inconsistent.