Removing these panels exposes a potential high risk rust areas which if these panels start to rust allows the ingress of water into the inner sills and lower wings. It’s worthwhile to remove these panels just to check for rust and if ok then to top up waxoyl or the underseal protection in there. I had to remove the covers to expose the door hinge nuts to be able to adjust the door hanging – see …….. https://mgb.tips/2020/03/24/exposing-door-adjustment-nuts-and-screws/
It’s important to get the seal on the panel the right way round and this post on the MGExp forum does a good job of explaining which is the right way round. Fortunately I replaced both the panels on my MG one at a time so didn’t get the seals mixed up. See …… https://mgb.tips/2019/01/07/wheel-arch-covers/
See the post regarding the seal locations here ……. https:/q/www.mgexp.com/forum/mgb-and-gt-forum.1/splash-panel.4197976/
This forum has a wealth of information about all things MG from across the world. The forum member who provided this solution for a member in the USA is based in Namibia.