Flat wrench. I hear the peterson's are good. The pry bar's look especially useful. You can cut a really nice flat wrench from good knife steel, or check out Kaotik's tension wrench HOW TO
http://www.lockpicking101.com/viewtopic.php?f=4&t=17220&start=0A smaller stem would be similar to choking up on the wrench you are using now. Not very comfortable. You can always bend a wrench to work, but in doing so you will change the feedback you get from it. Any way you toss it though you should learn how to use a different wrench, or another tensioning method so you aren't as tripped up by the locks position when it's less than ideal for your prefered style.
You've been a member for almost 3 months... DON'T pick your door locks. Picking practice is hard enough on brand new locks. Years of service plus picking can finish a lock off very quickly. It sounds like you might be locking yourself outside to pick if the door frame is in the way. Also unwise for many reasons. Anyway maybe you find a piece of my post is helpful.
-Tooly