Many thanks Stephen...
I would like to put a pier in as it would save some equipment lugging & make alignments & PA so much easier but, alas I suspect Min. War & Finance will not be keen on a pier & a circular pad...
I'm still thinking through my pad design & whether to mix the concrete myself or get someone in to do it professionally (significant cost differential I think). The marking out, digging & form work will be all me.. Min W&F wants it slightly subsurface but, I'm not entirely sure how to accomplish that with good screeding (I think that's the term). Still gotta contend with how deep (or not) the old septic tank is...
Once I get my Nth/Sth line reliably down, I'll probably look to make some indentations in the pad to enable me to place the tripod feet in the same spot time after time after time...
Not withstanding cost of your pier, seems like a fairly cost effective outcome...
Cheers