API Usage for Ordering VMs

We have been using MIQ (currently ivanchuk-2) for near 2 years now and our users have been using the UI. Just recently had some requests for our users to use the API for ordering their VMs so we are going down the road of making all of the same functionality from the UI useable through the API. We offer 2 catalog items, 1 for ordering RedHat and 1 for ordering Windows VMs.

Curious if this is recommended and if so, my main question is how do people handle the dynamic fields that have been created to automate some of the provision request data?