Found them!

I finally found the bypass valves on my 181.

1. Prop up the mattress.
2. Remove two screws on the far left piece of plywood.
3. Raise plywood.
4. Hot water valve is right in front of you. The cold water valve is directly below it. Small hands are recommended for the cold water valve.

Glad you finally found it! If you are like me, it kept bugging you until you found it. BTW, looks like we'll be neighbors @ the rally. We'll be in MS 280. We are from KC, & my wife is from Springfield. Her Mother, sister, & oldest son are still down there. See ya @ the rally!