Measuring Book Cover Appeal when Your Audience is Not on Social Media

The current series I’m working on is Middle Grade. I know how important it is to get a cover that appeals to your precise audience. Thomas has done podcasts on doing A|B testing of optional cover designs on social media to ensure the end product will resonate and people will buy it.

However,

The target audience for my series is ages 8-12. They either aren’t on social media, or they shouldn’t be. I can’t use that to test my cover designs. Sure, their parents are the actual purchasers but most of the time the kid has say in what they want their parent to buy, so they are still the target audience for the cover design, more than their parents.

Anyone ever faced this or have ideas on how to resolve the problem?