TL;DR: Simple can work, I'd still add an extra pouch weakside on your belt or your carrier if you can clear it. I always run side plates. Pistol mags on belt. Zip-on packs are for team environments. Make sure you pick a high quality, proven carrier like a JPC 2.0, Spiritus LV119 or Ferro FCPCv5, etc.
What I run is 4 on the carrier, I really want to go back to 7 though, even if it does suck in the prone the carriers aren't as bulky as they were back in the day and neither are the pouches.
Right now I carry 3 in front on a placard with an admin pouch in front I use a faux Spiritus Systems CCS to carry batteries of all sorts and an Android phone running ATAK along with a goTenna Pro X ranger banded to it. It's an old AOR1 24 shotgun shell pouch with the centerpiece cut out.
I do use side plates, using Hesco level 4s on the side, it adds some rigidity but if you wear them properly they should be covering the sides of your lungs and not just your love handles. Keep in mind it'll be anything from 0.5-2.0 inches of internal circumference taken upper if you're using a 3rd party cummerbund. So if you have thick plates and a Medium/Large cummerbund fits snug, I'd go with an XL and lace it tigther to your carrier.
On my left side I have a Tall Esstac Kywi, running a bladder on the rear, Ferro PTT retainers for my PTTs, Crye Precision MBITR wings on the front to hold a Hytera and a second radio or other BS using AXL adapters buckled into the side of my AVS front pouch to keep them from flapping about like actual wings.
On either side I have old Trident T3 TQ pouches, running a Ferro Dangler velcro into the inside of the front platebag to keep it close to me that holds the IFAK and another staged TQ right on the inside. And a shit ton of gloves. AXL zipper up top for the JPC 2.0 to use as a better admin pocket which holds my pro mask chinstrap extender, my AMP downleads, and a spare USB-C.
I don't wear pistol mags on the vest, I just carry 2 on the belt plus one in the pistol itself. Some of the more modern placards like the Haley Strategic and the new Spiritus Systems Micro Fight Mk5 have areas you can side mount more pistol pouches, but I'd likely use that space for a multi-tool and SDR dongle if I had room for it.
Belt also has another rifle pouch, TQ pouch, dump pouch, second blowout IFAK (in case I scuttle my armor after some Fed phaggot blasts me in the chest), and then an admin pouch with insert I can stash my nods in, and holds basic crap like reports cards, lockpick set, waterproof pad and pens/pencils.
The whole zip-on packs or MOLLE'ed in packs on the back are situational. I had pouches on the back of my carrier to keep extra charges, my NVs, and wet weather gear which someone else could retrieve. For being solo? Not much of a purpose there, better suited with a dedicated light ruck or assault pack. I have been using my old issued "Gen 1.5" SATL since it has enough standoff to not fuck with the stuff in the back.
Other extras are some Ferro retainer roll-up velcro I use for the bladder hose, and I run up the antenna relocation whips through my shoulder pads. Using A&A Tactical padded shoulder pads for a bit extra comfort. Just make sure you're properly fitting your plates, getting multi-curve plates, getting the right size carrier and picking a high quality one with Nylon/Tegris/etc. like a JPC 2.0, AVS, LV119 or Ferro FCPCv5
