That's something you might want to talk about with Mike at Heritage. They have a process, and it probably depends on how much of an upcharge it would require. Under the CC portion of the website they mention their "bespoke" program.
I don't know where you live, but if there is a dealer anywhere close, you should check out the current line. I didn't feel like the necks on the Standard II guitars were toothpicks! The couple I picked up were comfortable. I've felt much thinner necks. The 530 I bought in '25 is the original Standard line, but the neck isn't really any thicker than my 2005 535.
I hear all these comments about thin and thick necks, but for me, shape is FAR FAR more important than how thick it is. My 2014 Vintage '54 Strat has a baseball bat for a neck, but it's comfortable. My 74 Guild S100 is much thinner but I've played that for years! I've tried several PRS necks that were thin and were painful to play. I can pick up a guitar and can tell within 10 or 15 seconds if it's right or wrong for me.
And if cost were no object, I would just fly up to Kalamazoo on a private jet and visit the factory.... or else drive my Ferrari up there. Unfortunately, someone else won the $700+ million Powerball, so there's no private jet or Ferrari in my future!