That looks right. If I remember correctly--its been a few years. There was only 1 valve (I believe there was a check valve at the hot water out) so that when its turned one way the water bypasses the heater and the other way goes through it (actually a little simpler than the 3 valve setup in my Axis LOL).
From your picture I'd guess you're set as the valve is inline with the cold water intake (point the valve perpendicular to the cold water intake for winterizing).
In addition: Your picture of the switch would indicate that you probably don't have the electric option so you may not have to worry about burning out an element (that doesn't exist in your trailer).
Given what we're seeing: try it. Turn on the water heater for a bit and then open a faucet to see if warm water comes out (if you don't want to put any in the grey tank use the outside shower). You shouldn't have to wait for the water to come up to full hot...just long enough so that its warmer than the "cold" water.