Starting a full Dynamat sound deadening install on my 2017 ORP 4Runner (82k mi) next month (I have everything purchased). Just bought the vehicle this past January after looking for the right one since my daughter headed off to college 8 yrs ago – I’m a very patient guy lol.

I did a similar process on my 2002 4Runner (384k mi) 15 years ago and really loved the difference. It was my primary vehicle from 2008 till earlier this year - still my backup – I’m trying to hit 400,000, but the Wisconsin salt has hit me hard.

So a question that I don’t think I’ve seen asked or answered… If I’m mistaken, please let me know…

I’m doing the 4 doors first, than pulling everything inside out all the way to the dashboard – complete strip-out.

What other tasks, projects, mods, upgrades, maintenance, etc should I be doing while I have the full interior pulled out?

I’m thinking I should clean out my moonroof drain hose for 1 thing… but what else to save from having to do it later?

The only thing i can think of is if you plan on adding any accessories that require running power, data or audio cables, do it while the interior is out.

If you are installing sound insulator in tailgate, order stronger door struts. I've used few generic options with bad fit an too much power. Best one I found is sold by Gobi: GOBI Rear Gas Springs - Toyota 4Runner 5th Gen with just right amount of power and good fit.

I was going to do the same thing to my 4R but did my F150 first, to see what it would do. Duramat on the floor did'nt do what I had expected for sound, But the doors did. work great.
You might want to reconsider and get some sound deading Insulation instead of the duramat. it will insulate better and install a lot easier.
Duramat deadens metal flex vibration, the floor in a 4R is corrigated enough to stop the vibration of flat metal. In the bed of the 4R you are just trying to supress outside noise.
I see this all the time on those TV car shows and often wonder if its really what duramat was intended for.
Try doing the doors first . with the window regulators and hardware it is a challenge. By the time your finished with the doors you may rethink the floors.

I didn't do the floor because of amount of hours involved and pretty happy with doors and tailgate install. Upgraded all speakers to carbon fiber cone ones from OEM+ while in there. Did not use $$$$$ Dynamat and settled for this product which works awesome for fraction of the price of Dynamat.

Run power accessories as other mentioned, change any gaskets that are passthroughs to the bottom of the vehicle from a plug to a marine grade passthrough for future access if needed. Doors and hatch will increase weight of those components, so struts on the back hatch will likely be necessary. I wouldnt worry too much about the floor as its very rigid, but the quarter panels and doors are very thin and the sound deadening will help tremendously.

I also used the stiles for a old scion xd I have about a year ago worked well , to be honest I just finished putting this product over the stiles .

GOSCHE 394 mil 16 sqft Sound Deadener for Car, 10mm Thick Sound Deadening Mat Materials Can be Better with Audio Noise Insulation and Vibration Dampening 9.8″x 15.7″(15-Piece)

It is a foam to lay over the stiles had a bit of a problem laying everything back over it was pretty thick but worked ...