Dear robertmontgomery
The person responsible for support on RT is not available until the 13th, so I hope I can assist you effectively in the meantime.
I do not see why this would be a problem. Since the items for rental are sourced from Inventory Control it would be a matter of adding and identifying these "sub-rental" items in IC. In IC, as long as your Category and/or Account Set setup for those rental items correctly reflects the G/L accounts involved, RT should pick that information up.
If you keep your normal rental items in RT's "serialized items" area (ie your reference to "rental stock"), I don't think you would need to setup these types of items in the RT Add/Modify/Delete Serialized Items area, since they are not major investments on your company's part. This area is normally used when you have purchased items specifically for renting and would need to keep the RT files updated in this respect. However, since RT maintains the serialized item file independently of IC & does not verify that the number of units entered in the Serialized Item file matches the total quantity on hand (or out on rent) in IC - you may want to consider this before making a decision.
Regards,
Softrak Support