A problem is that the snowblower is a very awkward piece of hardware without a good central lift point on it and a tendency to rotate and wiggle around once suspended. Thus, when you pick it up, or try to, it is likely to shift and jerk adding dynamic force to what you'd like to be a gingerly almost stationary force/weight. You say "from a freight truck" which probably means you cannot get your loader bucket above the blower while sitting on a freight truck bed. Hard to make suggestions without pictures but I would TRY to get the blower in the bucket if at all feasible and strap it in to avoid jerking around. Then just see if you can lift it a couple of inches. With the snowblower around 50% of the weight of your entire tractor it will be precarious at best. The backhoe being on there has to be a big help. Make sure you have plenty of air in the front tires. And plenty of helpers standing around to watch and cheer. Better yet borrow a bigger tractor !
I know, I know, we ALL try something once in a while that would never be approved much less recommended by safety people. This brings on a sea story, of course. I once hauled a 900lb+ wood stove to a remote location where the ONLY way to get it off the truck was my B2150 Kubota with a non-standard Case loader having been adapted to it. Without adequate thinking (and being alone) I dragged/skidded the stove which was on a pallet off the back of the truck with the loader, very carefully going slowly and watching for tipping and whether the loader would support it. Sure enough the loader supported it (stationary) with no problem. That was stationary. I lowered it to the ground. No problem. Then tried to lift it back up a little with the loader and NO WAY ! The loader had the umph to hold it but not to raise it.
Might be possible to lift it off and down to the ground with the backhoe ? If so, do not rotate ! Have the truck drive out from under it and then lower it to the ground.
Good luck but borrow a bigger tractor if possible.