I appreciate that concealers have been your best option to-date and the concept of not using them is unthinkable, but............ and its a big but......... I promise you that when you finally do stop using them and switch to a piece, you'll realise how awful they were.
The time, the mess etc will all be behind you and its not until your free of them that you'll understand what I'm saying.

Best of luck.

PS. I agree with starting off with a lower density at 55%.
It will be less of a shock for you and those that see you.
With time you could go thicker.

If you want to keep the hair you have at the front, then this is the sort of template area you should be thinking about.