Cover available with water hose connection
yes you can buy a cover that will fit over where your hose fits to dump the tank. This allows you to connect a water hose a back flush the system. You will want to at a dump station or place that would allow you to dump immediately after back flushing. I actually put some chemical into the tank from above before doing this. Also, don't forget to keep that grey water valve closed during this process. The more times that you can do back flush and drain will insure a cleaner system. Walmart or RV locations will have this specially designed cap for your sewer line.
1993 22L HiLo
2006 King Ranch Ford F150