You have everything cranked up to 8? That is... quite ambitious. The 'standard' level for minor factions and AI plots is 4. One doesn't usually turn them all on at once, either. The minor factions have pretty varied effects on difficulty, but the AI plots are all straight-up pain with no benefits to the player, so having them all on is going to result in tremendous pain, even at Diff 8.6.
You need superweapons. You need them ASAP. You have four exos charging: botnet, golems, spirecraft, and alt-champ progress. Have hybrids shown up yet? You do not want them running amok; high level hybrids can build additional hybrid spawners, eventually resulting in them reproducing to overwhelming numbers. You'll be dealing with Trains, too, but happily Nuclear trains only show up at Intensity 10.
I took on Diff 10, but I only turned on minor factions that were beneficial to me, and no AI plots, and easy AI types. I cheesed it, basically.
Some of the shorter range turrets have radar dampening at Mark II and above; this will force the missile guardians to close with them in order to attack. I would pick up higher marks of Needler turrets since they have bonuses vs Artillery hulls.
Heavy beam cannons can put out a lot of damage, and they may be able to chew through H/Ks if you can unlock high enough marks.
I think you can probably afford a fair amount of AIP at diff 8.6, so I would use warheads liberally and rush the Fallen Spire campaign. Get far enough in that and the rest of the threats will start looking a lot less scary.
Check out the "Ride the Lightning" AAR for strats.
