The issue with taking dutasteride and letro simultaneously is that they will both be mutually less effective. DHT is one of the most important hormones for blocking estrogen at the receptor sites and managing serum levels, and for that reason DHT alone can reduce gyno symptoms. The more DHT, the better when it comes to treating gyno.
I have done exactly what you are contemplating, except with finasteride instead of dutasteride. The results were mediocre (maybe a 70% reduction?) and it came back pretty much immediately even though I was using tamoxifen at the end. A lot of this had to do with the fact that I did not taper off as gently as I should have.
What I would recommend sounds strange but it is working extremely well for me. I've powdered my tamoxifen pills and mixed them with some Cetaphil lotion. My dose is around 2mg tamoxifen every day along with two drops of exemestane (which is highly androgenic by AI standards) rubbed in completely, and this is working extremely well. The logic is that using this method, you can be 100% sure the drugs are penetrating the target tissue. I can feel a small "head rush" after several minutes, which tells me some is getting absorbed, but the effects on gyno reduction are profoundly improved compared to taking 20mg tamoxifen per day along with exemestane.
I also had side effects from tamoxifen orally, which I do not experience nearly as much from the topical form.
This is, again, just a personal experience. I also recommend creatine for increasing DHT levels as this will result in around a 10% rapid reduction on its own.
In total, I have reduced the size of the tissue from ping-pong ball sized (flatted and spread out) to raisin sized (flattened and spread out).
The only hair loss I experienced from all of this was when I was megadosing exemestane and injectable GH. I gained a lot of muscle during this period (and body hair), but hair loss is expected when running an AI solo. Using Nizoral on its own and no other hair loss products pretty much arrested the hair loss I experienced during that period. YMMV of course, and I'm still a NW1.