What is the f ratio? f8 perhaps? An EQ6 is great for that size. In the classifieds is a mount Astroboy (Zane) is selling which is a total bargain and perfect for what you want....but looks like it could be sold already.
http://www.iceinspace.com.au/forum/s...d.php?t=142556
I have had a 6" f8 on a motorised EQ5 that was OK and did better with a home made wooden tripod. As for a surveyors tripod....don't see many of these around so I think maybe not for 15kgs on top.
Matt