help Pillar for skyt2 mount

[theskipper1961]

Firstly it's good to be back I have been away for a while due to illness but I am all sorted now  .. my question/ any help you can offer me on my pillar project would be much appreciated , I have had an old pipe flange machined to fit the mount which works well the next part is the bit I am unsure of , my idea is to use a heavy gauge pillar preferably round 4mm gauge wall thickness  with a welded top the same thickness that I could drill and tap 6mm and fix using 6 mm socket caps stainless , 5ft high with 2ft in the deck / concrete with power for lights and  heat .... this would mount my Tal 100 Rs  or and the skymax 150 pro  I am unsure of the 5ft high may be make it taller or shorter  ??? And ideally I would like to get a stainless pillar  the o/d would need to be at least  160mm as the flange O/D is 145 ....

I would like any idea's or considerations you may have to help me And any one know where I could lay my hands on a pillar that size I have searched ebay to no avail .. many thanks Steve