Want to get around the mandatory enhanced campaigns for Google & Bing? Would you rather show your ads on mobile only?
Bing Mobile & Tablet Modifiers
Unfortunately the tablet modifier can only be increased by 20% in Bing so you can't make tablet only campaigns. You can however make mobile only (or almost mobile only) campaigns by lowering CPCs by 66% and raising the mobile modifier by 300%. This works best if your new CPC is lower than the first page bid for desktop.
Google Mobile Modifier
This 300% mobile modifer works on Google too but one account we work with saw a possible penalty. Mobile performed much better than Desktop in this account but we didn't see that reflected in the CPA of the campaigns with the mobile modifier set at 300%. I can't confirm that a penalty was placed on that account for trying to skirt the system but those are the facts.
The Bottom Line
You can get around Google & Bing enhanced campaigns, you just need to get creative