Mighty Mouse
It's All In The Reflexes!
If 40psi feels better to you than 42 on the rear tire then do it. If 39 psi feels best to you on the front tire then do that also. The 2 pounds will make no difference except possibly shorten your life of the tires by a few miles. Lets say one good burnout. Most riders aren't as anal as some of us (Me) and maybe check their tire pressure once a month. If you feel more comfortable with your selected tire pressure and it's a good ride then you're set. The suspension on the newer Rockets is good but not great. I have spent way too much time on the suspension trying to fine tune it and it's fine for now. I have certain factors I have to incorporate for my riding. Some of us want comfort and others the best suspension for back roads or a little of both. So what's comfortable and acceptable for a touring guy isn't the right set up for a back roads guy or a 0-100 guy at the track. I have found something in between and it's nothing like the set ups on the Youtube videos or the Triumph Manual. Weight/riding style/old injuries' are all incorporated into ones choice of what's the best set up for them. If dropping or adding a few pounds to the tires makes riding bearable on your old back injury then do it. 
