Woocommerce set user role at checkout

I'm creating a webshop in wordpress/woocommerce. My goal is to set different prices for different user roles. I already achieved this by using the "WooCommerce Role Based Price" plugin. And you can select a user type on the register page with the "WP Roles at Registration" plugin.

But my problem is: I need a select field on the checkout page to select one of the 2 user roles, and update the price if a different user role is set.

I searched everywhere for a capable plugin or code. I am fearly new to wordpress and I hope someone here can help me, I've been stuck with this problem for 3 days now..

via Chebli Mohamed