Congratulations for an elegant and promising construction!
Just as passing Idus in March, I think it is appropriate to align your outlook towards Handy Andy; he also built a good system on his pickup, but not long afterwards it fell apart, as he ignored what happened below the bed!
Now a looming breaking is seen on the video between
6:17 / 10:28 and
6:42 / 10:28 … A real salt-water basin! Without drain…
So, you better buy ortho-phosphoric acid and apply in two rounds, washing thoroughly the “skin” in between. Wait 2 - 3 days in between the treatments and afterwards!
Then a two-component “icebraker” epoxy, later covered by a bitumen layer coating…
When the spring gets warm.
To prolong the valuable acheivement!