Are there any existing passive DIY designs that get coaxials working well?

A few drivers i'd strongly consider using are the

Seas T18RE
B&C 8CXT

The coaxes alone won't cut it, I want to keep excursion (and IMD) to a minimum by adding a woofer or two - flanking the coax - WCW is an option, but i'd be rather interested in alternatives like rear or side woofer placement if the passband is appropriate

A sealed or TL box is one of my hopeful goals. I only really need bass down to 60hz or so of course. Box size won't matter as long as I can fit it on the ~ 20 x 60 TV stand Box height between the TV and can be around 14 inches

My source of inspiration is an active 2.5 way design that uses two T18REs vertically with one tweeter disconnected. I was hoping to keep it in the passive realm though.