There are a few reasons why I'm thinking of going this route.
I have a very specific size and dimensions that will fit my needs. Countless hours of searching online yielded a few options that would work. I contacted the company and they are "custom" and would take 6+ weeks but due to covid there is no guarantee on timeline. It is also nonrefundable.
The fresh tank is 1/4 the price and will be here in 2 days.
My plan is to get a flange like the one pictured. I have a CNC so I will make a 2 peice bolting flange to go on the inside from HDPE. It will be installed with a good sealant and stainless steel bolts.