I would remove any small branches around the tops, cut loose, then take away, do not leave any slash under feet. best working with 2nd person diong this. start out near the tips, sutting the small stuff, untill you an get close to the main parts of the tree & to get the equipment out of harms way.
using tractor to assist you in cutting is probably not a great idea in my opinion, sure to support the main part of truck, or to prevent it from twisting back at you but lifting something that size with anything ligher than a 50+ hp tractor is asking for some problems if it lifts it at all...
limbs that are UP off hte ground can be cut small sections at a time let drop down and clean out away from tree. just like smaller sections, working way down to trunk. Leave larger branches in place that are contacting the ground to support the tree as it sets. After you have the slash and most any and all self supported limbs gone take on the main trunk areas and any limbs that are supporting the trunk half as it is setting.
rember that you CAN use the tractor to help you in moving the thing if it is setting lop sided then by all means chain & pull it around and or over so that the branches and more limbs can be cut back as before.
Durring all steps be sure to keep tractor out of way incase the thing wants to twist & roll over. (AS WELL AS YOU'RE SELF
) DON'T cut to much off one part of the tree move around the crown taking out parts evenly so as to maintain ballance of the load on the branches that it is resting on.
Make sure you have extra bar & chain handy, so you can/could remove the bar if you get pinched any and put on 2nd bar. if the weight is suspended Up (base holding end high in air) then cut down from the top, if the limb end is laying on the ground and weight pushing down then cutting UP from bottom at angle so when weight comes down the cut opens UP freeing the bar to finish cutting up from bottom.
mark M