Marketpress with Authorize.net SIM

I’m trying to find a solution to replacing the form on this page.

https://www.maxwelldriving.com/classes/four-hour-court-class/

Currently it sends students off to TransNational payments to purchase a particular class date/time selected from the drop-down form.

Everything is completed offsite and the only data sent from the form is the selected class and some ID for TransNational in hidden fields.

The driving school has switched to Authorize.net as the Gateway, which won’t receive simple select forms like this in the same way.

So I’m looking at more WooCommerce and Marketpress. It seems I only need two products (4 hour and 8 hour class) with the class dates as attributes.

I want to use Authorize.net SIM to process. Woocommerce can handle sending the checkout to SIM but building the products with all the selectable dates is awkward.

Can MarketPress handle something like this or is there a better way you can suggest for something this basic?