Story of five walk-ons. Two of them are my cousins once removed (different parents, both a year older than my son, lot of baseball players in my extended family), one a former travel ball teammate and HS rival of my son's, and the fourth a guy we know that transferred from a D3 to a D1 for various reasons. Both cousins were definitely "preferred walk ons." I know cause both their parents -- my first cousins were really happy about that status.
Cousin A didn't last through fall ball at his "minor" D1. Cousin B, who is a left handed pitcher, made the fall team, but was one of the last guys cut before spring at his mid-major D1.
The travel ball teammate actually made the team. He was strongly encouraged by the coach as a walk on. Don't know if he had the actual label of preferred walk on, but probably did. In two years has had a total of like 5 ab's, at a big 10 D1. He is a fast kid, played outfield. Probably would have been high on the depth chart at my son's D3. Mostly used as a pinch runner at his school so far.
The fourth guy, who was a starter his first two years at D3 made the team as a walk on at a Pac 12 D1, but has ridden the pine for two years.
Oh yeah, I almost forgot number five. Number 1 pitcher for my son's HS team, but a year behind my kid. Lefty that threw upper 80's, and had a decent bat, recruited late in the game as a preferred walk-on by a mid major D1. Didn't last through fall ball.
Bottom line. no matter what you call it, the path of a walk on, preferred or not, is not at all easy. I would definitely keep hanging in there and hold out for something better if I could.