My '88 Jamboree had an LPG detector at floor level that was hooked up to a solenoid valve at the tank. If the LPG detector was turned off, or if it triggered, it would shut the valve off and no gas would flow.
However, if you can smell gas at the tank, you've got other issues as well.
We don't stop playing because we grow old...We grow old because we stop playing!
2004 Itasca Sunrise M-30W
Carson enclosed ATV Trailer
-'85 ATC250R, '12 Husky TE310, '20 CanAm X3 X rs Turbo RR
Zieman Jetski Trailer
-'96 GTi, '96 Waveblaster II