Remember folks, there is a big difference between IBA certified rides and the Iron Butt Rally. The cert rides allow as much fuel as you want, you just have to get a receipt every 350 miles or less. The IBR allows a max of 11.5 gallons and tech inspection is no joke. I was doing tech on Sat for riders. Nearly everyone was fine. A couple of non-approved stickers that had to be removed. However, I did fail a fuel cell because the mount was very flexible and there were real concerns that it would break off in an accident, or that the mounts would fail before the end of the rally. The cell was cantilevered out the back and only had two vertical mounting points to the bike. The addition of two more metal braces to the rear of the cell platform made it much stronger and less prone to levering back and forth, which would likely have fatigued the original mounts to failure.
Rally rules change every year. Typically being updated to reflect new technology like TPMS and other bits. We have a few bikes running FLIR systems this year. I think there was only one in the previous years. Having finished the IBR in 2013, I will tell you that no IBR is easy. It's not about riding the miles as much as figuring out the routing and challenges with scoring to get a high enough score to be a finisher. Just riding the miles from checkpoint to checkpoint on time won't get you finisher status.
One of the coolest bikes in the parking lot this year is an '83 Honda GL650 with major updates and custom farkles. Adapted car alternator, large spin on oil filter instead of the tiny cartridge style it came with, custom full skid plate to protect it all, all LED lighting from the headlight to the aux light. I think the guy has more wattage available than most cars, (cop car alternator?), but it's all done so well that the bike looks like it came from Honda that way in 2018 aside from the '80's styling cues.
Fuel cells are about being able to stop for fuel when you want to, not when you have to. And simply put, you already have a lot of bonus stops, any stop you can eliminate saves time over the rally. Not being stuck in Eastern Oregon or NJ needing gas where there is no 24 hour fuel and no self serve in the middle of the night is also a perk. Most of the bikes here are running 8-11.5 gallons. But there are still riders with 5 gallon tanks too. A 77 year old rider is on an old shovelhead with just the stock tank, for example.
One BMW GS rider lost the final drive on the way to the rally. Overnight shipping of a new one from WA to CO where he was prepared to install it himself in the dealer parking lot. Instead they gave him a sweetheart rate and did it for great labor price, so he let them do it. That FD did have 200k miles on it though, so you can't really say much about that failure. Hopefully the new one will go the distance too.
At this point one Goldwing is down and the rider on a borrowed bike, one Super Ten down and the rider out. It's only going to get worse from here on out.