Botan'gs hole + wiper linkage removal

[Ronin]

I'll be taking care of the Botan'gs hole soon as my electric mirrors stopped unfolding due to water leaking onto the relay box and from my reading to do it properly I have to remove the wiper linkage so here are my questions:

1. What to best block the botang's hole off? I was thinking a stainless steel bolt+nut and cover it all in sikaflex

2. I've hear of some replacement bushing for the wiper linkage and that if the chrome on the ball joints has tarnished they wont last long, so I was thinking of replacing the bushings and polishing the ball joints

3. Is there anything else worth doing with the wiper linkage/ecu box out?