I haven't tried with sim but the technique to making consistent steep turns within the parameters in real life is:
1. establish your 45 degree bank angle crisply and coordinate your turn (center the ball)
2. immediatley crank in a little nose-up trim
3. apply a little additional power
4. Continiuosly monitor the turn indicator to maintain 45 degrees of bank and the rate of climb indicator to maintain the correct altitude
5. Begin your roll out approximately 1/2 the number of degrees that your bank is (i.e. on a steep turn, you are banking at 45 degrees so you would begin your rollout at about 22.5 degrees before the desired course-round it off to 20 degrees).
6. As you establish your roll-out, bring your attitude indicator to level flight, reduce power slightly and crank in a little nose down trim
The amount of trim and power you need to add and reduce varies by not only a/c type but by each individual airplane and by how it is loaded on that day. If you experiment a bit you'll find the right combination once you have mastered the basics. Then as is the case with many other pilot skills, practice, practice, practice.
BTW-real life flight examiners are usually just as tough on altutude, heading, angle of bank deviations as the sim check pilot is.