unless you need it to be panels you might do a post and rail fence. that way there is no timber (except the post) touching the ground, and you wouldn't need to dig out between the posts: just make sure the bottom rail is higher than your highest undulation 
dunno how post and rail compares with panels for price though.
also if posts are too high once installed you can always cut them once fitted so that there all nice and level.
dunno how post and rail compares with panels for price though.also if posts are too high once installed you can always cut them once fitted so that there all nice and level.
