Help: winterizing tiny plastic pond with resident frog!

Early this summer, we installed a small pre-formed plastic pond (3 ft. x 2 ft. x 18" deep at the deepest) in a raised garden. It's got a small pump without filter for a pump-style fountain. See photos.
The plants are two potted swamp milkweed. A frog I believe to be a green frog (species, not color) has been quite happily living in the pond since late August or early September.
We're sure this plastic pond would freeze and crack over winter, especially since we're supposed to be in for another bad one here in Pittsburgh this year. Last year we had a long stretch of single-digit temp days.
We put the pond in hoping to encourage local toads to flourish, but weren't expecting a frog. Not sure where he came from, but would like to be sure he can survive the winter.
Any advice would be appreciated, thanks in advance!

Just to explain the photos:
First one shows size of the pond. You can see Froggy's eyes just above the water to the right of the pots!
Second one shows raised location. It's on the south side of the house.
Third shows Froggy more close up, against the back side of the plastic pond. We think he was sunning himself at the time!

I would relocate the frog to a swampy area or creek. He will then hibernate.

I would love to have frogs. Our pond is about 3.5' at the deepest and doesn't freeze to the bottom. I have thought of putting a couple of pots of just plain mud in the bottom and introducing a frog to see if he would be smart enough to find the mud and hibernate in it all winter. A long stretch for us. My fish do fine since we solved the oxygenating problem by running a pump to a hose lofted about 2' over the water/ice. It draws from the deeper end and exits to the shallow end drawing water from the caves under the large rocks at the deeper end where the fish spend the winter sleeping. Oh, I see them now and again under the ice briefly in early winter, and find one or two toward spring or mid winter in the skimmer so I know they move about a little.

You frog won't make it in a pond that freezes to the bottom, although I have heard of some frogs that can be frozen solid and then revive in warmer weather. Their cells are quite different from the norm. Don't think your little guy probably qualifies. Buy a fish tank and put mud in the bottom and keep it in a cold area to drop the temp to dormant stage with slight oxygenation? Garage or such. Seems if you take him to a lake or stream you will lose him but better that then to have him die.

I think relocating him to a pond or lake would be easier than trying to get an aquarium and meet all the necessary conditions.
He had to come here from somewhere, maybe he'll go back when the weather gets bad?! And come back here next spring!

Isn't there something you can sit in the pond that keeps it warmer to prevent freezing? What about a frame of sorts over the pond covered with plastic and heated with a few lightbulbs?

Can't help with winterizing a pond. Thankfully never had to do that (yet).

Your frog looks like a big one and really cute.

If I ever have to winterize my ponds I'd have to buy heaters. My son uses one in his little pond cause its on his lanai in shade and he keeps orandas. My ponds are in shade also but they just have always made it thru so far. My old pond has a plecostomus about 2 feet in it and they are supposed to be kept warm but so far he hasn't croacked.

Your pond looks very nice.