Has anyone integrated the measurement of a propane tank?

I have a client with a seldom used mountain home that wants to have access to propane levels in his (10) 1,000 gallon underground tanks. There is currently not wiring, conduit or power from house to tanks but could easily be run. I talked to the 2 major propane suppliers locally and as much as I tried, they both didn't seem to understand the question. A google search turned up this [Link: wirelessmonitoring.centeron.net] and there is a reference to it in a cepro article Julie wrote a while back but no details as far as integration other than it was with crestron. I have sent an email requesting info from the manufacturer but have not heard back yet.

I am using RTI and can write a driver to talk RS232 or IP but just need a valve that will give me the data.