Dimmer switch

[1carguy]

I have a Jayco Eagle HT FW that has 6 ceiling mounted main lights. When turned on these are super bright and way too much light. I wish the 2 lights in the hall were on a separate switch but they aren't and I'm not willing to tear apart ceiling and wall panels to access the wiring to rewire these on a separate circuit.

So, another alternative is to install a dimmer. Seems that all the 12V dimmer switches I've seen are 3 wires. The switch that controls the lights now are only 2 wire switches. I'm assuming that the 3 wire dimmers need a separate ground. If I'm correct, that means I would have to try to fish a wire through the wall and find a ground somewhere. Am I correct in thinking this? Any easier solutions?
This is the type of switch I was thinking of using:

[Vicr]

You're on the right track however what ever lights you want to dim needs to have its own dedicated ground wire connected to the dimmer. I have installed 4 dimmers in my Precept but only where I was able to fish the dedicated ground wire to.

[1carguy]

I was afraid of that. I'll give it a try, but if I can't fish a wire through the wall I'll just live with it the way it is rather than tear everything apart.