The trigger is soft brass, it'll bend quite a bit before breaking, but once it's broke....oops! You can anneal the trigger with a torch in between bending sessions and get it to bend even more. Brass tends to work harden, so when you bend it you actually make the trigger more brittle, the more you bend it, the more brittle it gets until...."plink!". If you anneal between bendings you will be able to bend it until it looks like a pretzle if that's what floats your boat. You can get a replacement trigger blade from Xisico for about $5. Go to the Mall section of the forum, lookup either Bestairgun.com or Sportsmen Target.com, either of those sites will have some contact info for parts which will give you the phone# for Xisico.
The stock on my B50 was way too long for me, and I'm a decent sized guy. The B51 I believe has exactly the same LOP as the 50 variant. So what you said about removing the buttplate is spot on for 99% of people....not including gorilla armed DaveD:) What I did was removed the buttplate, cut 1" off the stock, reinstalled the buttplate, and sanded it back in to the contour of the stock....of course I also bedlinered the stock first because I don't care much for "Chinese Mystery Wood"...yes, I am a wood snob:)
Just doing those two things helped the feel of the gun a whole bunch...the hardest part will be keeping it full of air:)