IFAK-
I would recommend just using your pockets. For me that would be more reasonable than an ankle IFAK. You can make IFAK supplies pretty compact. They dont have to be in the same pocket. It could be broken up into two pockets. Youre working low vis work.... nothing wrong with doing stuff on your own instead of buying something off the market. Hell, if it was me I would probably have the IFAK broken up into the essentials, bare bones, and going from there. Wrap a rubber band around it and I would call it good.
Armor-
since you are required to use level 3A soft armor I would try to keep the plates to a minimum at possible. I wish they would forego the soft armor requirement, because that stuff is bulky as hell, makes you sweat like a MOFO, and overall is just a PITA. Youre wearing civvies for christs sake. Anyways, since you dont have that option I would suggest something like a JPC or BFG plate minus. Something that is low profile as possible since you already have the extra bulk and weight with the soft armor. Even though you arent humping up mountains..... you will still appreciate the weight savings if time came to actually use the damn armor. Is there a way for you to take out the issues soft armor and put it into another carrier that might accept the Swift clip placcards and plates such as something by Velocity systems? That way, you have a all in one kit ready to go compared to multiple layers.
Loadout-
I would rather have more rifle mags than pistol mags on a battle belt/ PC. If you are pulling out a PC, in my mind, you definitely would want a rifle at that point as well. So, I would personally just run 4 rifle mags in total with an extra pistol mag or two on the battle belt. One rifle magazine in the gun, two on the 2nd line, and one on the belt. You can always have more rounds stuffed into a pocket if there is a Armageddon scenario or staged in a vehicle. I dont know about you, but if Im a cop and need more than 120 rounds or so.... something is seriously fucking wrong in my eyes. You can do alot of damage with 120 rounds. Spiritus systems seems like a better way to go for you due to your SMG and Shotgun requirements. They have the inserts for 12G rounds that can be in a pouch, and make a 4 mag sub gun insert. I would go with them. Im getting ready to pick up a full system to replace my rack minus chest rig. The low profile version, scalable, flexibility of the Spiritus systems rig is way more appealable. They Haley rig is nice. Ive never had any experience with it, but with what your requirements are.... all your kit could fit on a Spirtus systems rig and be smaller than the D3CR rigs. Two mags in the insert, along with a motorola.... then having a sub gun insert handy along with the 12G pouch insert on the Dangler or main pouch in front of the Spiritus mag shingle seems to be the way to go. Thats what I would do personally
Overall, KISS, low profile, and light weight. Cut what you dont need and keep the essentials. Dudes over here in theater with bulky ass kit are realizing standard RFI Issue shit is garbage and cumbersome when climbing up mountains. Guys who used to talk about wearing soft armor and side plates dont anymore and think its dumb. They had to learn the hard way.... almost falling out on mission. You dont have to luckily due to your environment.