In the Dez? I'd recommend FirstLite's 3D Leafy Jacket, or the Killsuit Mesh-ghillie SAPR suit from AllPredatorCalls.com. Those two are lightweight, and have GREAT air-flow in the Heat. And roll-up small in your pack.
You said you post-up on a ridge, so I assume the eCaller is down on the flat in front of you that you can see well in your FOV.
Even though you're up there, are you backed-up against some kinda bush or something so your outline is obscured? And are you being careful to not be turning your head back-and-forth while scanning your FOV while you're eCaller is playing?
Just like you, as a predator, they notice motion VERY well.
And their Hearing? Is INSANELY good! So make sure you quietly clear your throat and take care of all that fidgeting BEFORE you press play!
Are you trying purposefully to be as QUITE as you can when you enter the area?
Also when entering the area... are you doing so like a stalk? Depending on the topography... you might also have to concern yourself with being busted visually by yotes that are there that you don't see yet, as you make your way to your intended sit spot.
If they bust you, visually, that's it. That spot is done. Like sometimes if you're approaching a BIG DesertHills Mountain, there likely may be several fingers you end up wanting to hunt along it's bottom by the flat. Sometimes ya might have to "take the long way around" instead of just going up and over one finger ridge to get over into the next one, because they might see ya otherwise and bust ya. Again depends on the topography of the area and how educated they are to the hunting efforts there.
Typically they say to "Call into the Wind". BUT.. if you're on the edge of their area and the Wind is flowing into their area... Just make sure YOU are setup crossways to that wind coming off wherever you have the caller stuffed up high into a Juniper. So that YOUR scent (or your trucks scent) won't greet their nose on their way in to the eCaller.
Works really great to stuff it into the Juniper about chest-height on a branch up higher off the ground so the sound carries well and ALSO.. BONUS! when they come in, since it's up high... they end up stopping to then try to extend themselves up to look up to try to checkout where in there the racket is coming from. THIS buys you even more milliseconds to make the shot!
I personally don't take the motion decoy with me anymore. Had a hard-charger in my highly pressure area I visit come in hot, then hook a hard 90 degree when he saw that motion decoy.
If your goals is cats? DEFINITELY use the motion decoy! It'll keep 'em there, and hold their interest for quite some time!
And if an area is brand new to you. I just consider each new outing as a chance to potentially mark a new area OFF the list as a "Nope" if no takers come in. You know, when you're carpet-bombing across an area that's new to you. Make sure to cover a realistic distance from where the first set was, to yur next set location, so your next new area is out of ear-shot to sounds that WOULD HAVE emanated from that prior calling spot.
And make sure you're giving it like 10min or so after you stop calling, before you go fetch the caller. You'd hate to educate them by going to fetch your eCaller too soon while they're still around somewhere to see you enter the scene and become educated that all this exciting noise means "Him". Rather than prey.
Try to find places that seem to be near areas where like you've spotted a decent amount of Ground Squirrels... or like, you've seen good amounts of Quail up mulling around in the area. Or like, if on the drive in, you saw some Rabbits fightin each other on the road illuminated by your headlights? THAT is an EXCELLENT area to make a set at!
And if there are maybe rock formations, or concrete drains/tubes/tunnels that might present with collected morning dew water at first-lite, those can also be places Deer and Coyotes might try to slip in to in the morning to try to catch a slurp of water before it goes away.
ALSO since it's Dez, consider your vehicles smells and it's visibility to them. Ya don't want your vehicle to be something they can see sticking out like a sorethumb in this area of theirs where vehicles don't normally go to. So when you can, try to park it behind some finger or large bush that will obscure it from view of any yotes that might be higher up the ridge when they enter the scene.