I had the dash out two or three times on my 2008 HR Admiral, which is the "twin" to the Monarch. Here's what I found:
1) The jack panel could be removed and replaced without taking the dash apart. There was at least a foot of slack wire behind the jack panel.
2) There is "extra wire" or slack inside the dash, in places.
3) Unhappily, due to:
a) Monaco's wiring practices the slack is not where you need it or is wire-tied together
b) the air conditioning outlets attached to the dash panel
c) the radio
or a host of other details I was not able to remove the dash panel with the attached wires and components. Everything had to be disconnected.
4) The panel gets brittle with age, and must be handled with care to avoid cracking, especially at the screw holes and corners.
Regarding access under the driver's seat, I recommend you remove the seat from the post, then remove the post from the floor- the latter action only if you can unbolt from the floor without putting a wrench on the nuts. On my coach, Monaco welded the nuts in place, making it an easy unbolt from the top.
I have worked on the wiring without removing the driver's seat, but if you have to get under the seat it's a lot easier if it and the post are out of the way.
You'll find the plywood panel near the steering wheel shaft is just a cover for a steel plate. Getting behind that plate is very difficult.
I should have recommended this at the top, but before opening the dash I suggest finding the fuse that feeds the jacks and making sure it hasn't blown. It could save you a lot of time and effort.
I have wiring diagrams for your coach. If you send me a private message that includes your e-mail address, I'll send the diagrams to you. (Note: I seem to remember that I sent them to you previously.) Don't "publish" your e-mail address in public here, or the spammers will get it. Instructions on sending a private message are here