I use PML adjustable density as well, however I have found it starts to thicken or expand somewhere around the one min mark. Bottom line is that the two part foam options will provide a small window so you have to be organized.
I foam all my fin cans, I just foamed three 3" builds, 1 with a 38mm MMT and 2 with 54mm MMTs...limited space in the 54mm, but workable. As recommended on the PML instructions, I usually foam in small sections. One thing that I have done to help this is to make a paper shroud/funnel. Covering the MMT as the shroud and the funnel on the outside of the BT. This way you can just pour around the outside and let it drip into the cavity. Where you will have issues with this technique, is where it drips down it will start to expand out and block the cavity. So I usually use one spot, per cavity, to pour the first batch letting gravity settle the liquid before it starts to expand. Then when it expands I still have room to pour the subsequent batches, normally 3 at most.
One other thing about the PML adjustable density foam. When they say add a drop of water, they mean a drop or whatever number of drops depending on the density you are trying to obtain. I casually added a splash of water on my first batch and what a mess. I essentially ended up with a cavity full of foam that had no structural integrity at all. I had to remove it all and start again. I now just use it full strength.
