Is this the sort of thing that's intended to be used in caravans and
boats?

I think he means the type with the cistern and pan made from the same
moulding.

What's with this "copious amounts of silicone"? I've fitted several
close-coupled toilets over the years - and have never used *any* silicone!

Lucky you!

The sealing plugs must have actually stopped the water leaking out, which
not everyone finds to be the case!

Christian.