Group Window Minimalist?
 

Is there a way to slim vertically the group window to only show the members and their health, even having the member name superimposed over their health would be great.

You can use the custom layout tools to do something like that. Start with the EQII Default starter layout, then move spells, pet and detriment blocks outside of the green shaded area. You can shorten the group member tile (background size) down to 40 pixels.