4.5" tall Gusset corners are not available from 80/20 vendors, but you can get raw stock of the profile and machine your own using these parasolid or pdf files!
.x_t parasolid & .pdf Files will be available for download after payment.
Full How-to Guide & Bill Of Materials is posted online for free at: https://www.tacomaworld.com/threads/how-to-diy-wedge-camper.604686/