Any particular reason why you would just get a wider wheel? I'm guessing cost? Although, older rim brake wheelsets can go for like $125-200 around here. Pretty inexpensive, just want to look for the good hubs so you can rebuild them in future if needed. I picked up a beat up Major tom, White Industries set with tubular glued, used it a season, then re-built it and have it on backup bike now.

I run 28-32 psi with tubes on aforementioned set...but 19mm internal rim. Obviously depends on course. So with a 15mm internal you're kind of hot air ballooning the tire, which could lead to more pinch flats and squirmy feel.

My first cx wheelset was just stock generic, cheap and man it was squirmy. I didn't know it until I upgraded. Gives a lot more confidence in corners now and much more predictable.