If you have a 2" BL, and you want 33's, on 5.5" BS rims, you do have to trim PLASTIC...but not metal. If you have less than 5.5" of BS, you also have to trim metal to fit 33's.
35's are not only going to protrude ONE more inch UP than 33's (2" of DIAMETER = 1" more RADIUS)...
..so, as far as HEIGHT, sure a 3" BL would give that one more inch to allow the tire to rise.
The issue is that the 35" diameter tire's radius ALSO extends fore/aft, as well as up/down.
THAT means that the part where the back of the front tires was kissing the well's back end with 33's is kissing one inch deeper...and that's metal there.
So, the added 1" of BL over the 2" BL DOES help, a lot...its not the only thing you're going to need to do....to fit 35's.
To clarify, the main issue is the rears of the front wells, but if you don't have a Shrock, etc, the tires CAN also hit stuff to the front, etc.