surely it'd be better to commerate Everest being succesfully scaled the first time with NCC 52953 or 29553
I thought about that, but I admit I had the disaster fresh in my mind because I'd just watched the IMAX film about it. If it's a better idea to celebrate a successful summit, then that's fine.
Perhaps those dates you mentioned would be better attached to the actual names of the climbers? USS Edmund Hillary
, USS Tenzing Norgay
(if there were to be a ship named after Hillary, I got a great motto for the dedication plaque: "Well, George, we knocked the bastard off."