Slight bend and canting the bow. I only tree stand hunt when in Canada for Bears. I practice hard from a friends ladder stand 12 ft up since I bowhunt everything else from the ground.
I also aim using split vision. As I'm aiming and concentrating on the vitals, in my split vision, I pick my broadhead up BELOW THE ANIMALS STOMACH.
this is from 12-15 yds away. If the animal is closer, the distance between my broadhead and stomach INCREASES.
At 20-25 yds, the angle is decreased so my broadhead is usually right in the middle of the animals body. At 12-15 yds, if I was aiming and my broadhead was in the middle of the animals body....I would hit high or miss. Same if the animal was closer, steep angle, would result in a bad high miss.
It takes practice from 10-20 yds to adjust from shooting at elevated stands. If you have a longbow not cut to center, you'll need to cant more, almost laying the bow flat. always aim a tad lower if in doubt but consistant practice is the key.