I agree the best method would be to remove the shell from the frame and add some new framing in, however if I was to do that I think I'd just put in a new floor anyway, if I'm going to go that deep probably best to do a solid fix instead of building on the older floor.
However I was hoping to reinforce the floor without needing to remove the shell. Im a bit torn because while I'm not 100% satisfied with the strength of the floor and the uneven surface, I am also not convinced it isnt haha. Although the floor has a bit of flex it seems solid and there is no signs of rot underneath. I figure if the floor has lasted 30 odd years it is fairly well put together?
I think I'm hoping there's a fairly quick way to add some reinforcement that will also fix/help to level and give me piece of mind (I may be dreaming
) ................or someone to tell me everything's going to be alright and all bolers are that way and they can support an elephant