All of the above^
Although I'll say I'm not a fan of throttle locks. I'm just not a fan of the idea that they allow you to take your hand away from the throttle, and more importantly the front brake lever. A simple cheap crampbuster however was a godsend to me on a long trip.
Many folks I've seen that get cramps in their right hand are getting this from just gripping the throttle too tightly. That's why I prefer tacky rubber grips...I can hold the throttle open by just barely gripping it.(Still leaving a finger or two over the brake lever)
Any long trip your main concern should be your comfort. If you're not comfortable in the saddle it will wear on you. Also there may be areas that will do that, but won't show up until you have gone a few hundred miles. Seats being the biggest culprit here. The first 110 miles were fine, but suddenly your ass starts feeling pain.
I also suggest planning not just your route, but your stops. That 350-450 mile thing may be a stretch for someone that's never gone that far. If I'm doing a 560 mile trip, I won't try and do it in one day, I'll break it down to two 280 mile legs, and I'll already have booked a motel at that halfway point.
Same goes for gas stops. You don't want to find yourself near empty and not be sure you can make it to the next station. Planning helps here. You can always alter things if you want, but having reasonable goals for each day will make you more comfortable and relaxed.
I won't travel at night, so I try and plan my overnight stops so I get there in time to relax, have dinner, and get enough sleep before leaving in the morning.
I'd also suggest getting a dedicated GPS. They not only can be used to plan your route, but give you information on where to eat, where to fill up, and give alternate routes if you find the one you originally mapped out won't work because of accidents or road closures.
Good luck and happy motoring