Okay, so other than having my head examined...let's get that out of the way first.
I've been shooting 4x5 for ten + years now, and have my darkroom all setup. My "plan" is to use 8x10 for contact printing, so I am not worried about an 8x10 enlarger.
I've got a a camera coming - although it needs a 8x10 back still. I suppose that's important. . Lenses I am good on, right now my G-clarons will cover 8x10 just fine. I have a couple of good tripods that will hold an 8x10 no problem.
I have one single 8x10 film holder , lots of 8x10 trays, lots of chemistry. But I am just thinking, what else am I missing.