Decided to undertake this project since I’m replacing the Captain seats and have access. The dash was loose and crooked and I just wanted to make it solid and hopefully more quiet. I’ve removed the front and top dash. The wood support that projects outward needs reinforcing and the plywood base...
On my '18 29M, you have to first remove the flip-out desk (four screws in each of the bottom hinge brackets), unfasten the 120V receptacle and stuff it back into the dash cavity, then remove the two remaining screws that hold the pan to the dash. The pan will lift out enough to disconnect the 12V receptacle plugs.
Once you do all that, don't be surprised if you still can't get to the blower motor...
I replaced a squealing HVAC blower motor in our 2015 ACE (2014 F53 chassis). The flip out desk was easy to remove (as described above). Below the desk, above the passenger footwell, is another separate section. It was attached to the main part of the dash with a number of square drive wood screws. Most of those screws were not easily accessed - they were likely put in before the entire dash was installed - and were much longer than necessary to attach the panel. It took various combinations of ratchet extensions, flex heads and contortions to remove. IIRC, some I got out by removing the dash vents and reaching in through those holes. Finally - the blower motor was accessed.
I re-assembled the lower panel with easier to access screw locations using proper length screws.