Met Pengoquin this weekend and toured his modified 29M and was inspired to fix the soft shower floor in mine too. Well, several hours later, success. My shower floor is now nice and solid. Also added a USB port on the back side of the bed - (my side), a chrome tip on the gen exhaust and several pockets for the DW to store her iPad, phone, etc.
Shower support - as has been posted before - there is access under the shower in the right rear wheel well. Extend your Lippert jacks and then raise up the rear of the coach on manual as much as possible. I found it helpful to throw an old sheet over the greasy wheels. Remove access panel and measure 2x then cut wood to support the huge hole that Thor cut for the drain. My wood support was approx 5” x 7”. I put a 1/4” cushion on this piece of wood and then cut 2 vertical support that held the 5x7 in place. Screwed angle brackets into where the supports meet each other and now the floor is reinforced. It was a real jigsaw puzzle and PIA - but it was solved. Photo shows the panel to access the shower drain in the wheel well.
USB port was wired into the 12v supply for the outside kitchen light. The wires were accessable under the bed where your pillow would go - 2 screws! (Looks like I need to touch up the underside of the port where the wood hole is visible - oh well - no one sees behind the bed except me!)
Chrome exhaust tip was the same one referenced in this thread early on. Bought on Amazon. Just had to trim about 4-5” of the original pipe off using a cutting wheel. Easy peazy. Great idea to whoever did it here first.
The pockets for the DW were available on eBay from somewhere in SE Asia - they were designed to go between the front car seat and the center console. Less than $10. DW didn’t need a full “armrest” some have installed. Tried to find something that matched the trim already in the coach. Mounted using 3 self tapping screws each.
Have a list of 25 other more expensive mods I want to do - thanks mostly to this thread - now to get the $$ for all of them. Just booked Grand Canyon & Sedona for April.