I have made a few piers now, I would recommend ditching the stainless pipe. You will have to get a stainless base plate amd gusseting and that will have to be tig welded, in other words you are looking at cubic dollars.
Stainless has great thermal properties tho.....
I spoke to fahim about a pier and he showed me this pier adapter
http://www.losmandy.com/access.html. This adapter makes it very easy to make something up yourself.
Brett