So, just to recap the options to fire the camera without touching the shutter button:
1. Wi-fi, using the ImageSync app. I find the wi-fi connecting a bit clunky, and with the app you are limited to single shot firing. But you can control other aspects which you can't by other means.
2. Wireless remote. Receiver is at the front only. Can be used to fire the camera in various modes, including timer, with mirror up.
3. Shutter release app on phone. Does the same as a wireless remote. I use this with the app "DSLR remote". It only works if your phone can fire an infrared beam. My Galaxy S5 does, but I understand a number of more recent phones don't.
4. Tethering. Don't know anything about this.
Failing that, there are the timer options in the camera.
I just use my phone, because I have it with me. Using the remote with 3 sec delay setting, there is time to reach around to the front of the camera, fire the shutter and get my arm out of the way. A bit awkward, but effective.