By creating the proper FieldLayouts, I've been able to have single field CarouselItems, with just the particular field I want to show. The problem is that the whole CarouselItem is not selectable. Only part of each item, and it varys depending on where in the carousel the item is, will cause the item to change to a Highlight color, signifying that clicking will now select the right item. Otherwise the program thinks you're selecting an item that the cursor isn't over.
I can't find anything that is part of the XamDataCarousel or CarouselItem that controls the area that will be selectable, which I want to be the whole field/CarouselItem. The FieldLayoutSettings SelectionType members don't seem to affect this behavior (though SelectionTypeRecord="Single" does restrict the Carousel to single selection) and neither does setting the RecordSelectorExtent or RecordSelectorLocation.
The users will expect to just click anywhere on the Item and start working. At the very least they'd expect one consistant and obvious area to click.
This behavior goes away if the number of Items is set low enough to create a great deal of space between the items. I haven't experimented enough to identify just how much space, but one can definitely select on any spot on the item when the items aren't close. Likewise the expansion indicator works all the time in the same situation but sometime won't expand the child records when the items are too close. I don't know what settings might affect this behavior.