Just to add a few thoughts for the OP:
I'd fall in the camp of strongly recommending to go on with Private pilot, but I'd never simply refuse to train a Rec pilot student.
Yes, seems silly that the instructor's "club" would refuse to work with Rec pilot students. As mentioned, it really is the same PPL maneuvers and subject matter, minus the cross country, night, and instrument flight time. It shouldn't be any extra burden for CFI's or an examiner, at all.
In my experience, the biggest glitch in the concept of the rec pilot license, is that I have yet to train any students that would really be ready for any kind of checkride with only 30 hours (or, for that matter, only a very few Private pilot students are ready at the 40 hour minimum. Not saying it doesn't happen, but it's not the norm for the average Part 61 one-lesson-per-week student.)
After required fundamentals, part of the checkride quality proficiency comes from what I'd call just general stick time. More time at the controls, x-number of "extra" run-ups, takeoffs, landings, and just more hobbs hours to get comfortable, all adds up. So, if, after 30 hours, a student still needs 10-15 more, why not make some of those hours at night, some cross-country trips, etc.?
It's too bad you have to choose which path when it comes to the knowledge test, otherwise your idea of going ahead with the Private knowledge exam would be good. I might still recommend, continue with training, delaying your decision as long as is practical, to see how things look at, say, the 20-25 hour mark. It may provide a different perspective. That said, it all comes down to personal choice, deciding what will work best for your situation. Whichever you choose, welcome aboard, and.....happy flying!