I would be surprised if you got around not using a tailpiece below the basket. I use the best quality chromed brass tailpiece stock. I don't have much of a corrosion problem but I don't use salt water in our boats sinks.

This is the smallest marine sink I could find(Hamilton 12" in a tiny powder room under my stairs. It's sized for a 2" drain, which is the standard bar sink drain. It has a 1 1/2" tailpiece below the basket that makes it easy to connect an 1 1/2" chrome P trap.

Plumbing is easy if you have the right parts, but I don't think the right parts exist for you.

If you use a 1 1/2" tailpiece, then you have some options from that tailpiece, with adaptors, to get to your seacock. Good luck. Don't post photos of the finished drain line.