The aim of Caravan Toss might be very simple, but you need to work on your technique. Throwing a caravan is not just about brute force, but more about working out the best combination of throwing angle and force.
The optimal throwing angle would not necessarily be the same with obstacles as it is without obstacles, so you will definitely need to practice until you get the right combination.
Throwing Angle: Up and Down arrow keys
Velocity and Launching of caravan: Hold down the spacebar to power up and release to throw
...and remember, Caravan Toss is all in the technique.