How do you plan to anchor the ramp at the top or will it just lean on the entrance? Trying to get ideas how to anchor our ramp inside to the nestboxes as we need it to be removeable and not hinged or nailed down. We have a heavier new ramp and thought putting a cinder-block on the ground at the base of the ramp will keep it secure as it leans on the nestbox ledge. Any input? Thanks.