7% sounds laughably small
Hm, ok ... 7 % can be a lot, depending which minor state you have. Lets say Peru (fore example) has about 350.000 manpower: 7% are 24.500 additional manpower. Compared with USA or Germany it's nothing, but it could make a difference. Because you can combine it with "limited conscription" for your recruitable people and add even more with some of the land doctrines. Probably it would be the best to give a equal bonus to other ideologies.
You've badly misunderstood what the bonus refers to.
Let's use Peru as an example, a nation of 6.2 million people. With just the volunteer conscription bonus of 1.5%, you have 93,000 total manpower. Taking the 5% fascist bonus adds another 310,000 manpower on top of this.