Final answer:
To prevent colonists from moving west into the backcountry, policies like the Proclamation of 1763 could be enforced, restricting settlement beyond the Appalachian Mountains and using military enforcement, while also offering economic incentives for colonists to stay within designated boundaries.
Step-by-step explanation:
If I were the King of England and wanted to keep colonists from moving too far west into the backcountry, I would consider implementing policies similar to the Proclamation of 1763. This proclamation forbade colonial settlement west of the Appalachian Mountains to prevent conflicts with Native American tribes and to minimize the costs of defending and administering these distant territories. The enforcement of such a boundary could be done through the use of the British military and by restricting land grants in the designated areas. Additionally, an economic incentive system could be introduced to reward colonists for staying within the prescribed boundaries and developing the existing colonies rather than expanding westward.