Requesting 'fluid' ad size for DFP/Ad Manager

Is there a reason for the plugin to be setting sizes at all? I noticed in the other topic you said that if multiple sizes are set it rotates through them evenly. This explains another problem I’ve had and is behavior I don’t want. If I have 10 ads in size ‘A’ and 1 in size ‘B’, I don’t want those sizes to have equal representation.

I already have very granular control over everything in Ad Manager, so I really don’t need or want the plugin to do anything more than display the ad units from the tags I generate. Is there a way to do this and just display it in an empty, unsized div?