More robust spa response needed

[lucasnz]

As new controllers are added, we're seeing an increasing range in the size of the response. This is resulting in small tweaks to the response min and max values, leading to a less robust validation.

I think we should change the logic to check for a minimum number of fields in each row (R1, R2, etc), instead of the current logic that uses the total number of fields.

I'm open to thoughts on the best approach.