My area is architectural and structural so don't mind sharing some IP
With cylindrical concrete columns I found 10 cameras in a ring around the cylinder to be the absolute minimum to get it all to link together, and found 16 to be the practical minimum most of the time.
Humans being a funny shape probably require a few more setups.
You could try more stands with fewer cameras per stand, maybe 3 per stand on 13 stands, to see if it helps you register all the way around, then add more cameras when you can afford to in the areas you need more detail.
Another idea could be to use the 10 stands you have with 3 or 4 cameras each, and slant your stands at an angle so you effectively have 39 cameras evenly distributed all the way round horizontally, albeit at different heights vertically.
You can try moving the cameras further from the subject, up to a point, to increase their view around the subject and therefore increase overlap.
I have had success with focal lengths all the way from 10mm to 55mm on my crop sensor cameras, albeit only ever static objects with a single camera. I would say if you are struggling then go wider to increase overlap, but not to the point where your subject is no longer filling the frame, then zoom in until it stops working.
Back when Infinite started posting on this forum I saw he was getting results with 40 cameras, so it can be done (
http://www.agisoft.ru/forum/index.php?topic=385.msg1604#msg1604) but like ruffy says you have to experiment and it doesnt come for free!