In that case, once you find the optimum positioning for speakers and your head, you should find a way to repeat it EXACTLY when you put the gear back in place for mixing - things like pre-cut sticks for spacers between speakers and walls, pieces of masking tape on floors for locators, etc -
And yes, you should absorb the front wall ESPECIALLY with un-soffited speakers. Your wood floors and slat walls up front will make a bright enough environment.
You might want to make the overhead absorbers adjustable for angle, so you can experiment with lower front, higher rear placement at least for the two closest to the mix position... Steve