FT has come a long way since I found the site in 2016. The fleet of speed build kits and plans has increase quite a bit. I would love to see larger singe motor kits/plans offered. How about some 70-80" wing span flyers.
Larger planes require more money to build. There is a point where the price of a kit and the production run quantity would be such that the sales would be very slow or non-existent. As FT has a commercial heart and is not supposed to be a loss making venture. Providing larger planes in extremely small numbers does not make commercial sense especially where they provide free plans for those who would scratch build rather than buy from the FT store.
When you add to that the transport costs of ensuring that your ordered product reaches you undamaged and it quickly becomes a great loss making venture. Perhaps you could start a forum challenge for a 'Larger Design", (FT based). and see what it generates. There may even be someone in your local area who would be willing to assist you in making any resultant plans into a "Scratch built" kit for your usage.