Just a Covid quickie - lots of folks are buying these pools and looking for specially made bungee systems for swimming, tethered to a fence/tree, and finding such things are sold out. Not to worry it's easy to make your own with some bungee which is easily found on Amazon and eBay.
I've made lots of tow systems for swimrun and have used a range from 4mm to 8mm thickness of bungee. The thicker the bungee the less stretch there will be, 8mm seems to work well. In the video I've used 10mm as this is what I had handy.
You can attach to your waist, feet or both shoulders, whatever works best for you. If you attach it to your feet it's a good idea to use a pull buoy. Many swimmers have a tow-float belt which you could attache your bungee too, indeed any belt would work.
Some swimmers attach to feet and waist believing it to work the core better. Also worth noting that with the above pool your "anchor" could possibly be one of the aluminium struts.
If you are desperate then you could set something similar up with a bike inner tube and a bit of rope/string/shoe-lace.