We are laying a 14' x 24' paver patio. The ground is sloped on one side, with a difference of 12" in height from front to back. We can't dig down deep enough to level it because septic lines are underground. If we slope down 1" for every 4 feet, then the distance is only 9". Can we install two 1" x 6" composite boards (one on top of the other), stake them in the ground and have dirt behind them and then put pavers against the board as our border. We are 'soldiering" 6" x 9" pavers as a border. I want to make sure the pavers don't start to lean outward and we want the patio as level as possible because it will have a walkway from the patio downhill to a pier. Thanks!