Optimizing DV360 Campaigns: Dealing with Minimum Bid Requirements

I'm currently running a campaign in DV360 and have set up auto-bidding at the Insertion Order level to reallocate budget to higher-performing line items. However, despite setting a CPM cap of $12, I'm missing out on impressions because my bids are below the minimum requirement. How can I ensure my bids are competitive enough? Would focusing on deals over open auction inventory help, or would it negatively impact optimization? I'd prefer not to increase my average CPM, especially since these are video line items. Any advice or feedback on this matter would be greatly appreciated.