Staging the gun in the vehicle is indeed one option. Downsides include: adds unnecessary handling;
each shift is an opportunity for a passing driver or pedestrian to spot the gun, panic, and place a MWAG call;
can be forgotten;
may slow you down retrieving it if you have to leave car quickly in emergency.
Try moving carry position a little forward to 3:30;
invest in a holster that can be intentionally moved a bit forward when you need to sit, and then discreetly back to 4 o'clock when you exit the vehicle. For this you'll want very good fit between attachment loops/clips and belt.
A holster with a steeper forward tilt (butt)/rearward rake (muzzle) might also solve the problem.
There are also crossdraw, appendix, and shoulder rig options, but since you've already decided on 4 o'clock carry, these may not be perfectly satisfactory.
You didn't mention what you carry, but something as simple as a gun with a shorter butt might solve the problem.
Check out the auto parts store for seat protectors and similar options. Changing the configuration of the seat instead of the gun might be the answer.
Always trade-offs, aren't there?
Hoping this has been of help,