I know I am late on this forum. My husband and I have a remodeling business and what we have done in the past for owners who needed a really big doggy door was to custom order one. They can range anywhere from 200.00 and up but they last forever. We order locally from a place that does custom windows, also, a lot of your general contractors have resources. I am not saying order the doggy door itself but order a replacement door that has a customized doggy door in it. It does not take long to install them (should not take more than an hour if you have to replace the jam). It is pricey but if you are gonna be there for awhile, it is definitely worth looking into.