Good day.
A couple more inches has always been the story of my life
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Regardless of your length, I think first have to judge weather you can lift and hold the object, or will you be doing a controlled push/pull to manuever the object.
If you judge you can lift and hold the item (shed), then i think need to consider risk of drop…in that case consider how to secure to the pallet fork frame. If you have it secured (chain or ratchet strap) without much slop to the pallet frame and tractor can handle the weight, you should be able to lift / curl and get it up. If it’s too much weight be aware you are strappped in so to speak. If not on level surface or some sort of side slope, that a lot of extra leverage on the loader which could be transferred to front axle that pivots. That could go sideways fast and range loader frame or worse.
Be aware longer forks don’t solve everything…consider long forks on poorly constructed/deteriorated pallets (and to tip off even if the forks go through the pallet ( bottom side cross supports of pallet could be rotted or something and come off or not hold…point is long forks on a crappy pallet don’t always prevent a tip on an off balanced load…longer forks not always the cause of a tip/drop is my point)
IMO, first things first…Ballast appropriately. Think how to secure what trying to move. Go as slow as possible and as fast as necessary.
Good luck