Here are some shuttle ascent guidance basics so you can interpret my answer.
During first stage, the shuttle flew a predesigned (therefore open-loop) pitch-yaw-roll profile based, among other things, on the measured winds of the day. (Note that only the attitude targets were open-loop. The shuttle used a closed-loop control system to fly to those targets.)
After solid rocket booster separation, a closed-loop guidance scheme called Powered Explicit Guidance was used, which steered the vehicle to its Main Engine Cutoff (MECO) targets. During this phase, the commanded attitude was continuously calculated.
So, given that, even if the shuttle was flying a constant attitude, the engines would be continually gimbaling to keep the thrust vector pointed through the center of mass as the propellant was used up.
Also note that during first stage, attitude control was primarily controlled via the SRB thrust vector control, due to the enormous SRB thrust and long moment arms from the nozzles to the c.g.
I have some notes that show the center SSME pitch gimbal started out at about 4.25 degrees at liftoff, ramped up slowly to slightly over 5 degrees at SRB sep, then moved sharply to a little over 1 degree at sep. During second stage, the gimbal moved up slowly and wound up around 4.25 degrees again at MECO.
Please note that these gimbal angles are measured from the null mounting position. As you can see in this side view, there was a built-in pitch angle in the engine installed position so that the null mounting position pointed roughly through the average c.g.
The installed null position for the left and right main engines is 10°
up from the X axis and 3.5° outboard from an engine centerline
parallel to the X axis. The center engine's installed null position is
16° above the X axis centerline for pitch and on the X axis centerline
So the maximum angular deflection from the centerline of the External Tank that I know of would be about 5 degrees plus the 16 degree null mounting angle, for approximately 21 degrees. Given the rather strange shuttle side-mounted engine configuration, I'd have to say that your 45 degree gimbal angle is excessive, especially if you have a more symmetrical vehicle.
DOLILU overview presentation
Shuttle Crew Operations Manual 2-13.47