To me creating a high performance or ultimate plan turned out to be very important. Because you said you did go through the optimization guide (if I understand that correctly), I didn’t mention it, otherwise I would have brought it up.
So my advice: Should you create an ultimate plan: Sure, by all means!
Creating the ultimate plan (from a cmd running as administrator!):
powercfg -duplicatescheme e9a42b02-d5df-448d-aa00-03f14749eb61
About the missing power plans in general: Windows switched the way of doing power management: newer systems are using the modern way, (that is what you’re seeing) and there’s no way to create plans yourself in the gui. But when you create a plan using powercfg, it will show up and be active. Once you switch back, it becomes hidden again. 
I use a little tool (throttlestop). This tool makes it easier to reactivate power plans you created yourself. It can do a lot more, but some options require (expert) knowledge about undervolting etc. If you don’t know what your doing, leave those options alone. These are not on the main window anyway.
Hope this helps.