Sunroof seals or seal

Hi I am about to reinstall my sunroof, and have installed a seal on the front edge, however this has me wondering if it requires a seal on the back edge also, I can’t find any mention of a rear seal in the forum
Additionally I have replaced the old leather material the sun roof has for sliding on, for some cut down rubber hose, I am guessing the thickness required, has somebody got an idea of how thick these leather pieces should be ?

There is a thin layer of felt at the rear to prevent scuffing of the moveable panel. There is no real requirement to seal the sunroof from rain water. There is a drain pipe at each of the four corners of the tray. These exhaust into the four wheel arches and certainly should have their rubber tubes replaced at this stage to avoid headlining damage.