So after fighting with reliability issues with the DHT22's I've switched over to an HIH6130 sensor. It actually made the build simpler as there are less wires and both my temp/humidity and pressure sensors speak I2C.
We'll see how it goes long term.
My other concern with the lipo battery and it's projected lifetime seem unfounded. The whole system has been up for the hottest part of summer and very nearly the coldest part of winter and battery performance is still really good. Multiple days of runtime without sun would be fine. In saying that the new sensor may lower that a little as it's powered all the time