I wanted to use Thats Merc Life's armor distributions with Horizon v1.9+, but needed to fix and balance some things. I did change up some of the armors based on how they look, major changes below. Locations of NPCs and merc corpses were not changed.  Flagged as ESL

Installation:
-Download the requirements
-Download the patch with your preferred mod manager
-enable
-follow the load order
-endorse
-order pizza idk

Load Order:
>DT_MercOutfitPack.esp
>ThatsMercLife.esp
>Z_Horizon.esp
>MercOutfitPack_life_Horizon patch.esp

Changes I've made other than the balances
-Armor enchantments have been removed

-Helmets, hat, beanies, and armors that come with hoods or masks attached are now adjusted to match Horizons upgrade system. If it has a gas mask, it will have the same type of upgrades and augments Horizon's gasmasks have. If it has goggles or eye wear they will have the same type of upgrades and augments Horizon has, including gasmasks. This means, outfits like the Merc Renegade and Tech outfits should be the most sought after as they will have vision, gasmasks, filters, armor upgrade slots, augments, and utility slots.

Freed up arm slots to the following armors
-Merc Privateer Outfit
-Merc Wardog Outfit
-Merc Veteran Outfit
-Merc Grunt Outfit
-Merc Subjugator Outfit
-Merc Advisor Outfit
-Merc Surgeon Outfit, now has arms and torso slots available

Following armors are now considered leather 
-Merc Subcontractor (non armored)
-Merc Renegade
-Merc Veteran
-Merc Enforcer
-Merc Freelancer
-Merc Advisor
-Merc Drifter
-Merc Tech
-Merc Surgeon
-Merc Duster
-Merc Drifter (no mask)

-Fixed level lists to work with Horizon
Scavengers can now spawn with the following armors starting level 1 as level doesn't really matter in Horizon in my experience
>default outfits, Merc Drifter, Merc Advisor, Merc Surgeon, Merc Freelancer, Merc Duster, Merc Operative, Merc Drifter No Mask
Parsons Captain "Maria" can now spawn with one of the following armor sets
>default combat armor, Merc Heavy, Merc Tech, Merc Renegade, Merc Combat, Merc Grunt, Merc Subjugator, Merc Wardog
Parsons Guard "mercenary" can now spawn with the following armor sets
>default combat armor, Merc Enforcer, Merc Combat, Merc Grunt, Merc Privateer, Merc Subcontractor (armored), Merc Subjugator, Merc Wardog, Merc Subcontractor (non armored)
Edward Deegan can now spawn with one of the following armor sets
>Default combat armor set, Merc Combat, Merc Privateer, Merc Subcontractor (armored)

Credits
Mercenary Outfit Pack (STANDALONE) - DefaltTheFixer
Thats Merc Life - Mercenary Outfit Pack Distribution and Balance - Armighty
Horizon v1.9 - Zawinul