Can't help on your mystery switch, but your battery disconnect switch is probably located under your LP tanks in front of your battery. Most likely looks like this:
On some units your age (like my 2012 Roo 19), they have a push/pull type switch usually located near the power center. Looks like this:
Works like an old car headlight switch: Pull out for on, push in for off.
OR: You simply may not have one.
1988 Coleman Sequoia - popup (1987-2009) - outlasted 3 Dodge Grand Caravans!
2012 Roo19 - hybrid (2012-2015)
2016 Mini Lite 2503S - tt (2015 - ???)
2011 Traverse LT, 3.6L, FWD
2009 Silverado 1500 Ext Cab, 5.3L, 4x4, 3.73
2016 Silverado 2500HD Dbl Cab, 6.0L 4x4, 4.10