24' is a long board. 12 feet is a long board. 4' is a cut-off. 
I don't really do much about special handling even at 8'. Above that I would sit another SS behind the one I was using and set the table and fence the same (no blade). Think of Dusty's excellent set up pictured, just a separate unit.
I do like to keep several little thin wood wedges handy. I cut until the end is past the blade then stick a wedge solidly in the kerf to keep it open then just keep cutting. If needed I will stick another wedge in as I cut.
If you don't have or want a second SS maybe get an extra table and fence and build a simple stand for it or clamp it in something like a B&D Workmate.
Another simple solution is to just look closely at your existing table and fence and building something similar out of wood...
You can also look about the shop for jigs to "borrow". Example use a separate stand (like the afore mentioned B&D Workmate) to support something like your jig saw or band saw with a clamped fence and use that tool's trunnions to set your needed angle.
