No offense intended, but READ THE PERFORMANCE TABLE. I can't emphasize enough how important that is. That will tell you if a short field takeoff is necessary. I did a normal takeoff in the Warrior. Yes, you will need to lean at run-up prior to takeoff. For fixed pitch, lean for best RPM, either at run-up power or at full power. I'd suggest full power in an unfamiliar aircraft. You may need to lean for engine start (but I doubt the DA is high enough for that).
Other recommendations are:
1. Estimate Vy at altitude. It will be significantly slower than at sea level. In the Warrior at 8000 DA, it was in the neighborhood of 65 KIAS. I could get a 500 FPM climb at 65. A lot less at 75 (yes, I tried it). If you DO opt for the short field takeoff, Vx is slightly higher at altitude.
2. Identify an abort point on the runway before your takeoff run. Make it far enough from the end that you can abort the takeoff without overrunning if you don't like it. If the runway is long enough (and I suspect Big Bear is), the criterion can be 50 ft AGL by a certain point, which guarantees you can get out of ground effect or abort.
3. You're not going to get a 1000 FPM climb. Be prepared for that. In calm winds, a 200 FPM climb may look really scary, but it's still a climb.
For really high altitude airports, the standard technique is a soft field takeoff, not short field, to get the rolling resistance of the wheels out of the picture. Big Bear isn't high enough where this is essential, but you can practice it.