[QUOTE=GallopingGrape;3390851]
Generally a breast collar is needed if you are on the trails, going up and down hills to stabilize the saddle. You only need the front cinch, the rear cinch is used when roping, so when you dally the rope around the horn, with a cow at the other end of the rope, it doesn’t pull your saddle up! I like to use my rear cinch to keep my saddle steady, but it is not necessary! My gaited horse has alot of ‘swing’ in his rear, and the rear cinch keeps it steady.[/QUOTE]
[QUOTE=gabz;3394713]A breast collar is a safety item. In the event the saddle starts to slip sideways, the breast collar will prevent it from rolling UNDER the horse.
I suggest a quality neoprene or soft leather one. The fluffy ones collect seeds and burrs and whatnot along a trail. The nylon web ones get quite sweaty and can be hard to clean.
Please invest in a breast collar. : ) 
Rear cinch probably isn’t necessary for what you are doing. Unless you are very familiar with using them, I say don’t. I’ve seen some folks that were unfamiliar with them undo the front girth before the rear girth only to have a wild horse on their hands, or the rear girth is not adjusted properly … too long and it’s a potential for a hind foot getting caught in any precarious situation; too short, and you’ve got the potential bucking strap or - a horse that THINKS it can’t breathe and flops down on the ground for no reason.[/QUOTE]
All very true,
The flank strap if used must not be loose. Forget what you see in the show ring. What WP people do is often wrong. Snug it up just enough to keep him from hanging a foot in there if he kicks at a fly. If roping it needs to be tighter but it sounds as if you’re not intending to do any of that so just touching the belly not tight. Also use the keeper to attech it to the front girth. DON"T let it slide back too far!
Practical use for it besides roping is to minimize side to side sway when you ride down a hill. This can sore up a horses back. The flank strap prevents this so it is NOT as many believe just a useless decoration.
George