Hi @MNielsen85,
I think you could technically achieve this using standard objects and association labels. You could still communicate with all parties involved and track the associations between your partner and the end customer, at least at the deal level. You wouldn’t necessarily be able to track the association between a partner and end customer at the company level.
The custom object is the better solution in my opinion because you would have the ability to track all relationships, which will become even more important if there are multiple deals per end customer. Reporting would also be better using a custom object, at least from what I have found from similar setups.
Short answer: Yes, standard objects might work but custom objects would work better.
Josh