Shelly,
Sorry to hear about your Dad, I never met him, but this community mourns our losses. May he rest in peace and we pray you find the strength to get through this tough time. It sounds like you have things in perspective with the memorial.
As for the decal, I use Vista Print. With the Pinto Stampede I have had everything from window decalsand permanent stickers, to big refrigerator magnets that can be removed and put back on.
I think the memorial is a great idea, post some pictures, we would love to see them.
Norm