I think the 2.3 should work just fine for you. The best behaved all-round back tire I have used for summertime Mountain Biking (it's a new category of riding you can variably succeed at on any bike) was a 29 x 2.3 DD DHR Maxxterra. Anything I have used over 2.5" has been a floppy disaster on aggressive turns. That 2.3" DHR was supportive, not that heavy, just the right profile, rolled fast, and durable.
Try finding a 2.3" tire in stock anywhere though! Hen's teeth! People need 2.5" at least to ride a green trail.