First, do you have the large sink drain baskets(3 1/2") or the smaller bar sink size (2"). There are more options for the larger baskets including higher quality that work much better, and a better selection of piping pieces in 1 1/2". Plumbers putty works fine for sealing the baskets on boats. The 2" basket uses a smaller dia. and has less variety of fittings.

If there are no clips then PS probably didn't use them. Do you need them over a sealant?

Connections below, it's hard to say if there is a stock sink drain fitting that will work-tailpieces to baskets, coupling, tailpiece to hose, etc, but I doubt it. Hence the hodge podge. My galley and head drains are pretty funky, but they're safe.