Vertical speed line trunk wood onto brush pile or tires to minimize ground damage? Thats a great way to minimize shock loading for any dead tree rigging.
Strap or tie co-doms together is a nice way to minimize forces as well when topping into a block. I generally feel comfortable negative blocking dead trees (we do primarily Ponderosa, Lodgepole, Spruce, Juniper, Siberian Elm) depending on time dead, as long as roots are good and the ground can run em... I'm very risk adverse and play things in my favor.