2 questions- Fasteners and Sonar Wiring

[ProfessorLongArms]

I'm doing some maintenance on my Trident.

Both of these might be more OEX related questions...

Getting ready to add some rails on the sides or possibly some flush mount star ports. Because the Battery box in the middle of the Torque model is non-removable (at least AFAIK- Andy maybe you know better?), I can't get in to bolt it down as looks the most stable. . .

What's best? Rivets? Well Nuts? Self tapping screws?
So far, my guess is that it seems plastic rivets are smaller holes, no metal to corrode, no neoprene to wear out... OTOH, Well nuts *sound* a lot stronger.

Given these options, would I be limited in what they can handle? I can imagine a go-pro mount would be much less stress than a rod holder for trolling or a pulley rig for lobster hoops.

*Second Question*

I have a Lowrance Elite-5... It wouldn't power up on my last outing and I've been troubleshooting.

1) So far I found saltwater and corrosion in my little gasketed 5amp fuse port, and I'm going to replace that altogether since I'm not getting full voltage through there.

2) The unit itself also got wet on my last outing when it worked, and I gave it a light rinsing/drying when I got home.

3) I'm noticing a good bit of corrosion in the (cable side) female pin connectors where it plugs into the unit.

Actual questions-

In your experience, how waterproof are these things? What's the aftercare if you take a big wave and the unit gets soaked? I'm assuming you don't dunk the thing in a bucket, but I can't imagine it's as little as a damp rag.

How prone are the cables to going out? It's been a few years and I'm considering replacing the whole wiring setup so I'm not fiddling with it every other trip. Kinda sucked to get out on the water and fight with it for 20 mins and give up.