Call your local municipal office to find out if your city or state has a memorial sign program. Most do. Fill out the paperwork. This usually entails a commitment to keep this area free from debris. Have a ceremony to remember the lost loved one. Have the first pick-up session. Talk about how this person helps you through the journey of your life.
Most of my best memories of this person come from a road trip or traveling somewhere, even down an old dirt road. Whenever I am on this road, I think of him/her. So I thought I might as well make it a public declaration. I will always go through this life with him/her at my side.