Well, with less than 5 hours to penalty here at the finish, I can certainly tell you that a bike requiring daily oil changes would qualify as a 'Hopeless class' entry. The majority of riders have planned their routes to maximize the time allowed. Many will get in to the finish after 11 days with less than an hour to spare before penalty, many in penalty in the 2 hour window of penalty time.
During the 11 days of the rally many won't sit down for a meal, don't get off the bike at most gas stops during the day unless they need to use the restroom and all are constantly trying to manage every minute of the ride to avoid losing time that may be needed during the rally for bonus collection or unknown events like traffic, weather delays, etc. If you're not sleeping, riding or collecting a bonus, you're wasting time.
Until you have spent some time on the clock doing a rally it's hard to get your head around how easy it is to regret spending 20 minutes doing something you didn't need to do. Because at the end you may really need that 20 minutes, making the difference between finishing on time or being DNF. This year may set a record for attrition and DNFs.
Part of doing the miles is setting up the bike to be the most comfortable place to be. You spend a lot of time there over the 11 days. Little annoyances become huge annoyances over the course of those miles.
You didn't say how long it took you to put 10k miles on the Beta. I'm guessing over a year. Putting a year's worth of riding into 11 days is a lot harder on a bike than doing it over a year's time.
I'm not saying it can't be done, only that few people would even consider it. I don't think you would find anyone experienced in the endurance rally scene that would accept your offer of a Beta, even prepped with their input, for the IBR. Outside assistance is not allowed during the event. That doesn't mean you can't have someone help you get a replacement part or GPS, etc, but the number of GPS failures alone every year, never mind bike failures, is significant.
You talked about carrying a spare final drive belt for a HD. Most of the chain drive bikes are carrying a spare chain, sprockets and master links with the tools necessary to install them. That's a chunk of weight and space on a Beta. Add in tire repair kit and tools for that if you have to pull a wheel to do a tube repair. Every rider is set up to be able to eat and drink on the bike while moving. That is because dehydration slows down the brain and you start to make poor decisions. You can't afford to make poor decisions. So every time you think about being thirsty, you take a sip of water. Many carry a gallon, some two. Some carry electrolytes as well. The rally has had riders end up in the hospital for numerous reasons, from dehydration to hyponatremia as well as a variety of other reasons related directly or indirectly to being on the bike for so many hours every day for 11 days.
As stated, the temp spare belts for the HDs are only intended to last long enough to get you to a shop. Not hundreds of miles. A lot of things seem easy to deal with or plan for from behind the computer screen, but even on a big bike, you can only carry so much stuff. Riders have carried entire BMW final drive units and the tools to swap them out in past years. This year more than one rider is wishing they had done that, now out of the rally or on a second bike, (a 50% penalty in points at the end).
Got to hop in the shower now and go to scoring to get ready for riders coming in. Enjoy reading about the rally. Consider doing a 12 or 24 hour rally yourself to see what it's like to be on the clock and trying to solve the puzzle instead of just putting down the miles during a SS1K ride.