My hoophouse is pvc but I still utilize roll up side walls. I have 1.25" pvc pipe as my roller if you will. The poly is taped in a couple spots and rolled up about a foot or so before it leaves ground level. I just drilled holes through the poly and pvc pipe and use three inch long sheet rock screws to join it to my base board. If its calm, no wind I'll just put three screws in for the night. Otherwise I batten it right down every four feet.

Your Situation my be different (metal pipe/heavy) but I'd design several u shaped channels for the pipe to rest inside of in the closed position. Place one every four ft or so to get a good seal and design a quick clamp or just screw or lag bolt it for the winter. I would not bury anything in the frozen ground! Also, some commercial growers use 2x2" joined with metal as the roller and simply attach it to the base board everynight with two headed nails. Very simple. There is always the what if factor! Hope this makes sense to you.

What's your frame made of?
Ours is galvanized steel tubing and we installed wire lock on a baseboard along the bottom and we just wiggle wire it down during the winter. We also installed wire lock on the vertical part of the rollup and wiggle wire it down too. If you leave a little opening for the inflation fan to blow into the fastened down sides, you can inflate them too that way.

I orderd extra plastic and coverd the inside of the hoophouse from the hip board down to the ground with plastic and have a very good seal. I also have the same size hoophouse as you.