I Can't tell much difference between my old 2005 Wildcat 27BHWB @ 29' and our 2013 Wildcat 312BHX at 34'. I have a very tight squeeze into our backyard as well and find the 312BHX a little easier to back up.
I wouldn't worry about the 2'3" difference, in my brain I would consider those the same size.
I bought my 2007 LBZ 35000 with the P0087 problem towing heavy. If you have around 130k+ I would bet you need a set of injectors.
I know people say LBZ don't eat injectors, but the fuel quality and lack of good filtration seem to say otherwise. I can tell you my Efi live would not hit the max command PSI on a warm truck until I replaced the injectors. All the injectors were within "spec" on the balance test.
I would also suggest doing what I did as well: Add a Kennedy Diesel lift pump and mega filter. Also, only use the GM or Racor (same thing) coalescer filter. This should keep you from burning through another set of injectors. That is unless your near buying a new truck then just forget it.
Only purchase real Bosch injectors and expect to pay $3500 to do the job yourself.