Topic

I just might have a go at that myself.
I've used a marine grade nylon plumbing fitting for the TEE but there is no off the shelf 4-way fitting available so this looks like the way to go.

Just to update - 6 years on and still perfect, no problems. I finally got round to identifying the connector (for interest) and it's the PEO000010 four way connector. I doubt it will ever need replacing again.