Scan Guage looks like a great product but is not for the OP's year of motorhome.
I've had mine installed on my 2000 Winnabago for over 18 months. I would like to hear from you as to your reasons for this comment, which is entirely false. We just returned from a trip from CA to MO, gave me all kinds of info along the way.
It even works on my 1995 Avalon.