Sun does in fact make a trike that has a 400 pound weight limit so the industry does care about making trikes for heavy riders. Their model is the EZ-3 USX HD.
https://www.utahtrikes.com/PROD-11617617.html
Note the use of 48 spoke wheels. Smaller wheels are inherently stronger than larger wheels for the same spoke count. I once dropped my Greenspeed GTO off at least a 10" drop on to bare concrete with nary a problem with the 20" wheels. I'm not in your weight class but if I tried that with the 700CX23 rear wheel on my Catrike 700 it probably would mean a trip to the bike shop to have the wheel serviced. I see this version of trike come up fairly often on Craigslist and it gives me the impression that some people buy it only to discover that pedaling a 65 pound trike takes a bit of perseverance and willingness to suffer a bit. It's twice the weight of my CT700. Wheels aren't cheap. It probably would be better to look for one of these trikes on the used market and sell the one you already own. In the meantime if you are very careful your current trike will probably be OK. There is a bit of slop built into the 300 lb weight limit for the standard EZ3. Ride on smooth roads, avoid potholes, and don't go fast when you come to a rise in the pavement (like entrance to a bike path where the pavement forms a lip).