Possibly - It depends on all things being accurate in the first place. If you had a flat rail on your rifle and your scope set at optical zero you would have, in theory 32.5 moa adjustment up and down, however things are never quite so easy. With your rail already at 20moa and another 10moa with the insert your 100yd zero will be very near the extreme of your adjustment. I would go for the 5moa insert and give it a try. Remember, the the thicker insert needs to be raising the rear of the scope up a little more.
When you get to the range have a play with your scope from a 100yd zero just see how much actual adjustment you have and if the minute markings and click values are correct. with careful measurement, known velocity and known BC of your bullet and the aid of a ballistic app on your phone you will get a fair idea of where they will go further down range. One moa is 1.047" at 100yds.
Here's a rough "tall target" I used to see if I would have enough adjustment in my scope to shoot the .22lr long range competition at Bisley last month (200/300yds)
From the target I could see I would be ok for 200yds but run out of elevation before 300 yds - From there on it was necessary to use the internal hash marks on the reticle to get to 300 yds. Using this target I was able to get the first shots comfortably on the target at both 200 and 300 yards.
Starting from the 25 yard zero, each bullet hole is one full turn of the turret.
As you can see from the target, there's a lot of elevation adjustment wasted, a 20moa rail would have done the job perfectly.
