Very nice project!
The subject talks about 10DOF. What are the variables that you need to sense? (DOF means degree of freedom, right?)
In the subject of batteries there are big ass button cell batteries too, I believe that it can be a option too. But at the end, the best choice, I think that may be LiPo.
Why to you use "pre-made" boards, and not design you own board? It can have whatever you need, and can be of the size (or shape) you want. The other important point about this question is it can have ONLY what you need (and nothing more consuming your precious power).
Doing some math: if you have one battery with 1000mAh and you need it to work 70 days, the system need to consume at max 1000mAh/(70*24h) = 595uA. This must include the bursts of RF, save data in the flash/SD card etc. I think it can be done, but maybe not with any microcontroller/system.
The last question (that may be the key question) is about rate. At what rate you want to read data?