I am taking out the head because it has no holding tank. Don't have the
money, time, or inclination to install a
smelly holding tank.

After the head is removed, I still will have the two lines .. raw water
intake and smelly water overboard discharge.

Of course, they both go to seacocks.

I don't want to permanently remove the lines/hoses.

What should I do about them? Of course I will shut the seacocks.

Should I put a plug on the lines? Any ideas about using them for other than
turds.

If you have removed a head, overboard discharge, and gone with a porta potty
... even for part of a season or longer ..

what did you do about the existing lines/hoses?