Rusty, I think you've hit on the solution, mark the boundary conservatively so that where there is uncertainty you make sure your property is protected. Its not like what you're doing is a legal survey. That puts the onus on the neighbor to survey the land if they dispute the boundaries. After all its their actions not yours that have resulted in your losses (time, money, property damage). Edit: It if was me I'd only hire a surveyor if the neighbor agreed to pay or share the cost.