Jeg tror nu godt du kan bruge en mere eller mindre direkte oversættelse som fx. 'determined dreamer'. Det dukker ofte op i jobannoncer som et karaktertræk. Prøv at tjek Google.
Her er et andet eks.:

"As a determined dreamer, Phil brought vision and hope to a struggling congregation. His leadership helped the congregation to dream and to begin to grow so as to be served by a full time pastor. Phil’s energy and vision live on in the life and ministries of Community Church. Charlotte Dixon, Phil’s wife and our former choir director, is an active part of Community Church."

Håber det kan hjælpe.