I have a 535 Mossberg, with that short barrel turkey gun model.
I put on the Blackhawk stock that absorbs the recoil and is a 6 position stock.
I don't like the shotgun very much because it doesn't load and fire the second shot very well and a shotgun that doesn't work right it something that I need to either get fixed or get rid of.
As for loads..
I would tell you that turkey shot doesn't work well on predators. It may sound stupid, but some new shotgun hunters don't realize there is a difference between #4 shot and #4 buck. Be careful of this.
With that said..
The #4 buck didn't do well or group right with the turkey choke. Carlson dead coyote fixed the grouping of #4 Buck, and didn't work well with the Hornday coyote loads.
I can't justify using Dead Coyote, too expensive. But the Hornady coyote load has been working really well for me.. I like the increased number of pelets in the hornady load, and it works best with a Modified choke (as stated on the box)
I carry a shotgun to every stand, and set the rifle, ready off to the side, and hold the shotgun in my lap ready to go. If I need to shot the rifle, i usually have time to switch, but ususally have a predator surprise me in close. So i sit with the shotgun facing down wind, or at a spot that i would have a tough time swinging on if something showed up without being seen.
I have killed fox, Bobcat, and Coyotes with the shotgun. #4 buck and t shot are fur friendly, as long as it's not right next to you) and worth having on stand. Last year I shot the bobcat in my avitar with the shotgun at less than 10 yrds, and then grabbed the rifle and shot a Coyote making a run for it. If I had used the rifle on that Bobcat, it would have ruined it. As it was there was about 25+ small holes through both sides, but didn't blow a big hole or ruin the fur. (I would prefer a farther shot next time, but it dropped it dead.
If you use the shotgun for 40yrds or less, it doesn't really matter (in my opinion if you use T shot, BB, or #4 buck. They all work for this purpose, I just prefer more pelets, to give me a better chance at hitting something vital.
I would also suggest a small pistol for when you get up there to the shot predator, as a finishing gun. I have a 22lr pistol and use it when they aren't quite dead. A single shot to the heart, or through the ear hole, doesn't ruin the pelt and puts them down quickly and humane.
I carry the #4 buck in the truck as backup, but use the Hornady mostly.