Other alternatives

Don - I use my smart watch or put the camera on a tripod and use the timer function. Gives you up to about 10 seconds. 

Great idea

I have a handful of those

I have a handful of those little Bluetooth remotes.  Seems they hand them out like candy with most of your orders on Amazon if it has something to do with a Cellphone camera mount or holder etc.

The few times it would be nice to have one,  at a layout operating even etc.  but I never bring it and at home, normally do not tripod mount my cell phone for a photo.

Remotes

Oh, I do love a good remote and have tried more than my share over the years.

 Currently, especially when I am shooting focus stacks..........

iPhone 10. The camera is either set on the layout surface on a little doohickey holder or boomed over the subject matter with a tripod and extension boom. If I can reach the iPhone easily I just touch the shutter button. I use Camera Pixels software and have it set up with a 3 second delay which takes care of any residual vibration from touching the shutter release. If I want to fire it via wireless I use the ubiquitous little remote that Don shows in the first post. I don't use it often due to its habit of losing pairing with the iPhone at the worst times. A good compromise when you can't easily reach the iPhone is to hook it up to Apple earbuds and the volume control on the earbuds cable will trigger the shutter. Works great. I mirror the screen to my computer via Reflector 3.

DSLR. I've gone through several different models of those big ole' beasts. Several Canons and currently the weapon of choice is a Nikon D810 full frame with a 16 to 35mm zoom lens. This is my first full frame camera since the days of film and I'm having a blast. Thanks to eBay these babies go for a much reduced price when the newer models come out. Anyway, the Nikon, and earlier the various Canons are remotely controlled via USB connection to the computer and Helicon Remote software which gives the operator control of shutter release,  focus, shutter speed, F stop, white balance, zoom in to check details and some other functions that elude me now. The DSLRs can be set on the layout surface using small diver's shot weight bags to balance and stabilize but most commonly are atop a standard tripod. I'm currently putting together a heavy monopod system as the tripod can take up so much floor space in my small garage room that I have to move it out of the way any time I need to go grab something. Very frustrating. The picture below is the Nikon testing out different Rube Goldberg mounts and stabilizers. The black cord at bottom right of camera is a power supply that plugs into the battery slot. Very helpful for long shoots with "live mode" engaged.

Remotes with selfie stick

One of my remotes came with a selfie stick.  The phone holder on the end of the stick can often be detached, put on the phone, and the assembly set on the layout.  Quicker than a tripod, and very useful for taking focus stacks.

@Rick Nice approach!

I like how you’ve mounted things there.  Building on your idea, if tripod clearance is an issue, I think if a person inset some standard threaded inserts (1/4 x 20) every couple of feet along their facia, they could have a board made up that spans any two inserts and a mount on the board that allowed the camera to slide along to any position between the two inserts.  This would eliminate the need for a tripod and permit either macro work or wide angle landscape.  My DSLR weapon of choice these days is a little crop Canon M5.  It does superlative work and is a lot less weight to lug than my Nikon D200, D300.  Lately though, all I seem to use is the iPhone 12, which can shoot RAW.

Don and Mike

This is a fun thread!

Don. Below is a picture of the cell phone doohickeys I use. The one on the left has a quick release plate and is used on the tri/mono pod. The one on the right is for setting the cell camera on the surface and the notch in the base is so I can access the on/off button. Of course that notch was quick mod after using the mount the first time! Duh.......

Mike. The idea of inserting 1/4 X 20 connectors along the fascia is interesting. I especially like the idea of a plate that would serve as the camera mount. I'm not sure how to handle this on the curved sections of the fascia but I'm still chewing on that. 

Mirrorless camera.......boy howdy! Those are really cool. I looked into those recently and if the Helicon Remote could have worked with one I was ready to pop for one of those. My wife just bought an Olympus OMD Mark 5 iii and it is amazing. Camera technology is astonishing these days!