If I recall correctly, all your shots are at very close ranges, under 50 meter, no? At that distance, any deer that weighs less than 200 lbs. is fair game for your .45 using PRB. If you use conicals, you can take even heavier deer- up to 400 lbs. at those close ranges. That, I believe, covers most of the deer you are likely to find where you hunt, NO?
Understand that the .45 is capable of shooting to a much longer range, than 50 meters, but the PRB, weighing only 125 grains, loses a lot of its muzzle velocity- 45% loss at 100 yds compared to the MV---. Conicals help out a bunch, but the ROT for a PRB limits ones choice on how long, and heavy a bullet the same barrel will spin adequately to stabilize it during flight. With the Lee, R.E.A.L. bullet, or the similar bullet made by Buffalo Bullet co. ( the "Ballets") you can get deeper penetration at longer range, although the trajectory will be the same or worse with the conical compared to a PRB. I look at the .45 caliber PRB as being a 50-60 yard hunting round. The .45 Cal. Concals extend the working range out to 150 yards, but after that the trajectory makes range estimation very important to avoid missing the game all together.
You can target shoot with 40-50 grains of powder in that .45, and use up to about 60 grains for a fast, hunting load with the PRB. To burn more than 60 grains of powder in your .45, efficiently, your barrel will need to be longer than 33 inches.60 grains of powder will give you close to 1700 fps.MV in that .45, so its nothing to sneeze at. If you use the Swiss powders, the velocity will be a bit higher.