I vote no to the dump pouch. I hate fumbling for shells or making a shick shick noise when I run. I say no to side saddles and yay to butt cuffs. Side saddles interfere a bit with my peripheral. Esp. since peripheral is most important for sensing motion. Depending on where the thing is mounted it can interfere with the often sticky tang mounted safety. (esp. if a lefty)
Esp. relevant as a righty but also applicable to lefties is:
Under stress when doing a speed or combat reload it's easier just to slide the shell forward and under in one motion and tracking a clear visual path to the mag or port instead of having to switch over your hand to the other side of the receiver to shove it in the port for a combat reload or even worse, tilt the gun on it's side etc like with a side saddle. With a butt cuff you can start with the shell on the right side of the gun and use your support hand to keep the weapon on target (easier than trying to hold it from inside the trigger hand) while your trigger hand (probably your more skilled hand) does the reloading. If you need a demonstration I have a 590 I can show you with.
But when I reload, no one's life hangs in the balance so feel free to errr call the shots on this one (pun fully intended)
So yeah, just some velcro on the right side (if you are a righty) side of the stock should do just fine. Or if you are looking for something more secure, a neoprene butt cuff or similar. And then some on the shotgun cards. You have more options that way.
BTW: out of my own personal interest, do you get slugs
I take it you are a Navy Corpsman unless this is a recent thing for the 68Ws