I now have a system with 3 moteinos, one as the remote sensor, one as the permanent wireless gateway to my house RPi, and one dedicated to wirelessly burning the other 2 (and i've got plans for more)
didn't have much problem getting a python script to read in the serial data from the gateway moteino and posting it to Thingspeak, so i've moved on to ordering some bits and pieces. namely two waterproof boxes, i think i'll have the processor and battery in one box on top of the tank and the other just inside the tank with the ultrasonic sensor and cables for temp sensors. this way the battery is more removed from my water supply.
researching the latest/greatest temperature sensors i've settled on the LMT87 from TI.
also ordering a couple more moteinos, one for my under cabinet lighting needs and another for a (very) remote driveway sensor, solar powered.
thinking of laying out a shield with a LiPoly solar/charger and a coulomb counter like one of these. or texas instruments version. i would love to know such power usage details on a remote node. it could be temporarily attached just for initial characterization/tuning, so perhaps the coulomb counter should have it's own board, or even it's own arduino/moteino, report the data on it's own channel even.