Hi Gipsyblues I am only going to use the CubeCell capsule for package shock detection in transit.
My experience is the capsule and Board are the same electronics, I have focused on the Board Version as far more useful for me and will be basing some nodes on it, now I am happy with the software and hardware.
On the use of LiPo I have both 80mAh and 100mAh LiPo for the CubeCell and if you think the 100mAh is small you need to see the 80mAh, it seems so much smaller.
On solar cell charging I have used both Mono-Crystalline and Poly-Crystalline versions and in the range from 5- 7.5 volts (this is 10 to 14 cells), I based mine on 6 volts but 5.5volys is as good.
You ask about battery life , I put up a few months ago a battery life calculator on one of my sites https://securethings.uk/sdm_downloads that will help you with the SF/duty cycle etc.
On the solar cell size, then just base it on say a factor of two on the average daily use of the node. Typically in the UK for example 4-5 hours of poor sun light and with a 60 ma Solar cell this is keeping my nodes fully charged when set at sf 7-12 and duty cycle of 20 minutes TX 14dbm.
Happy Festive period Simon