There is often trouble caused when screwing in to wood on outdoor jobs. The corrosion one is obvious but less so is the fact that hardwoods will get a really good grip on the screws after a few years and stainless in not very strong giving rise to screws breaking off when you try to get them out - I have a solid oak camper van and the stainless screws invariably snap off when I want to get them out. A good alternative is something like this :-
https://www.tcfixings.co.uk/main/pr...mm-Wood-To-Metal-Furniture-Dowels-BZP/1. You can then use anti seize compound on the nuts or better still stainless dome nuts.
