Al wrote:

If it were me, I'd ask for the value of the proposed buyers house, and get
a covenant put on it such that it must be fenced/maintained, and only used
for foot traffic by the owners of the now buyers property.

I believe (although the book I read it in is not entirely up to date)
that you can't create a permanent covenant like that. Specifically, to
do anything requiring the spending of money. It will be binding on the
current owner, but not on his successor if he sells. The successor can
only be bound to do (or more usually, not to do) things that cost him
nothing financially.

Pete