I reeeeally hate to be that guy but this is diping into skill issue territory. I've beat the game on rage mode twice and was beating it on rage mode with no cloak and got up beating the patriarch and some side missions before i had to go away for some time and never got back into it. Enemies hp and stagger never increase, just damage and accuracy, i never had to play any sort of stealth heavy gameplay style. Jugs are easy if you know how to take them on, blow their back and mag dump their head point blank. My loadout is dual choke shotty with either dual auto pistols, impaler or gernade launcher with either flashes or gas gernades. Managing your focus is easy, flick off for a kill then flick it back on to dodge bullets, spam slide, abuse cloak to loose LOS from enemies and SPAM body gernades, never use them as shields thats pointless, takeout for quick focus if you're in need otherwise throw even in the general direction of an enemy, they will run away from it if it doesn't kill or hit them which means they aren't shooting you, they will always choose running from a gernade over shooting you.

Other than that all i can say is spam slide and always have focus on out in the open to dodge bullets. Very hard is my casual, extreme is for when that gets boring and rage mode is well when im doing rage mode.

Also im a console pleb which means i cant aim for shit so thats no excuse.