Wow - sounds like a fun trip!! We did Louisiana (New Orleans) to Vegas last year for the SLK World Retreat, and was absolutely great. We did "lower" route out, with a slight detour up to Austin to enjoy the hill country and see family, then out across west Tehas on the I-10 raceway, up through Roswell, NM to see the aliens, and across to Sedona where we based ourselves for a couple of days rooting around the Grand Canyon.
Other than I10, we tried to stay off the interstates and onto the state highways, etc - basically picked what looked like cool routes - and you gotta drive US66 just to say you've done it!
Didn't really notice much in the way of outrageous LEO presence, but I was running near the speed limit most of the time, and with a nice Escort 9500ci to keep me awake. The backroads tend to have the usual locals with speedtraps - some dropping from 65 to 35 in the blink of an eye. AZ has some type of mobile speed camera / trap looking thing strapped to the top of a van, but they got detected a decent distance away - seemed to be pretty low power transmitters.
I pack light, wife not so much so, but we did fine with a couple of duffelbag sort of bags "stuffed" under the roof divider. We are planning a jaunt across Europe late this summer, early autumn, and will more than likely just stage (ship) some stuff over to the various stopping points along the way - we've done that before, and it works pretty well - DHL to the place you are going to stay, with a pre-filled way bill included in each box for shipping dirty laundry and "picked up/must have" items back home.
Only worry on both trips is really having a flat - but with MobiLife on the '55 for Europe, and MB Assistance in the US, I guess it's no better / worse than anything else. There was an accident in the UK where a person was killed when the flat tire was put in the front seat with the passenger and it exploded and killed the passenger - so be careful if you had to do that.
Goal is to *never* have the roof not able to be lowered in an instant!
'Vegas got iffy on the way back as the wifey collected things...