You sure are right about the dust. That stuff is terrible for anyone to work with. I have found that PT (I call it Greasewood) will dull tool edges much quicker than most any other woods. I do nnot know if it is the chemicals or the moisture. If I were to have to, and I repeat have to plane or joint PT I would put old knives on my equipment, and then thoroughly clean my machine to remove any of that caustic dust.
Us cypress if you could.