Prime Rib Help!

Hoping someone can help. I've got an issue--I'm hosting Christmas this year, planning on making prime rib. I've seen a lot of great reviews of the reverse sear method, so was going to try that. Here's my problem.

We want to eat about 6pm that evening. We have a service we have to attend from 1:45 to 4:45 that afternoon. So obviously cooking the prime rib AFTER we get back isn't going to work. I'm left with either cooking it so it gets done (other than final sear) just before we leave, and letting "rest" on the counter until we get back, then final sear just before serving. Problem is, that is a LONG time to rest on the counter.

So my other thought was, would it totally ruin a prime rib to cook it almost all the way, take it out before we leave, and then either throw in the fridge (to stay cool) or into a cooler (to keep warm), THEN come back and final sear? Is this one of those "you really have to be able to cook it straight through, final sear, let it rest, and serve, with no room for downtime?

I have no idea how to go about this, or if I should just totally give up on the idea of prime rib and go with ham instead. Any thoughts, or advice, would be oh so much appreciated.