Yes I can edit the look and feel via the portal pages, stylesheets and layout areas, but I can’t experiment easily without affecting the live system – option to have different themes (each of which would contain the mentioned items) - this would also provide a revenue area for you too maybe - much like the WordPress theme market.
Also, it's not currently possible to upload images to use in the customisation - these have to uploaded elsewhere and then referenced, which is cross-domain and frowned upon.
This would be great! We would like to offer a super customized portal to our employees, and some sort of step up from just the "preview" option would be fantastic!
A dev site perhaps?