I have just finished framing out my theater room. It is 18.4 feet long by 11.8 feet wide. I would like two get two rows of three theater recliners in totalling 6. How big does the back riser platform have to be in depth and can the first row be pushed up against the platform. One person told me five ffet in depth would be enough room to recline and not bother the front row. Another person told me six feet deep. Is seven inches ok for the height for the height of the platform. Please help.