It might be worth looking on the internet/Ebay to try to find a replacement drain pan and just replacing the whole thing. Will cost a few more bucks, but in the end getting it fixed right will let you sleep better at night.
If you do replace the pan, go ahead and buy that torque wrench and torque the pan bolts per the mfg's specs.
Getting the drain plug over-tight is a common problem. I know from my own experience. I've found replacing the 0-ring each time helps prevent this. Although your particular application may differ.
Good luck and safe 4-wheeling.