Use of sales order line service attributes in Negotiation phase

Hello - we use Sales Orders in the Negotiation Phase to track client subscriptions to product we manage in legacy product systems. the only thing we do in EBS is bill the client for usage that is submitted from outside EBS.

We would like to track service_start_date and service_end_date on the sales order line as it is presented from the external product system.

Since the sales order lines in the negotiation phase have no workflow associated to them, and we are not converting our sales orders in the negotiation phase to sales orders in fulfillment phase, does anyone think that using the 2 service date fields could cause issues?