Necro-posting but so what.

My first IBA was a SS1000 on my 50th birthday. I kinda screwed up and ate something at a gas station that wasn't agreeing with me, and fell behind my intended pace looking for clean restrooms. But I completed the ride in the early morning hours. If you're interested in a ride report: https://www.riderforums.com/daily-ride/86403-50th-birthday-saddle-sore-1000-a.html
If you're plagued with the squits or something worse, IMHO that's a red flag. This a direct path to dehydration, a major no-no. Additionally, if you didn't bring along your NASA-approved Depends, thinking about "I
HAVE got to find a place to..." can be a serious distraction.
I'm not speaking from SS1000 experience, just riding (and LD driving) experience.
So, when opportunity next presented itself, I did a SS1000 and BB1500 combo ride just to prove that I could get the SS1000 right. And I did. And I also rode the Tail of the Dragon and the Blue Ridge Parkway on this trip. https://www.riderforums.com/general-ninja-650r/94009-tale-tail-dragon.html
Both while doing your SS and BB rides? If I were "on the clock", those are two places I'd avoid like grim death. The BRP, locked behind a 40' Class A towing a CRV. really and truly SUX! DAHINK

IBA is big on using the Interstate system and similar primary roads. It's easier to get around the Class A's there.
OTOH, Last spring, somewhere in OK, east on I-10, we hit an "everybody off". A bridge, almost within sight of the exit, was shut down for emergency repairs. The detour itself added ~30 miles to the trip (yea if on an IBA ride). We spent 10-15 in bumper to bumper jam, with no way to take a long way around with less drive time. The road grid just wasn't there. The jam turned out to be caused by a bubba that hadn't a freakin' idea about how to keep traffic moving. Past the bubba, traffic moved and life was good all the way back to I-10. Point being, Interstates are good but some days they become trap.
Main lessons learned: Follow the IBA's posted guidance, but when they advise to eat healthy, choose instead to only eat what you are familiar with so that you won't have a bad reaction to something new. Keep moving, downtime cannot reasonably be made up by going faster (and the IBA will refuse to certify a ride if the times look like the rider was unsafe). Headlight upgrades are a good thing, I bought brighter bulbs after the 50th birthday ride. And really know your route in case you have to alter your plans.
And this is a link to the IBA's posted guidance: http://www.ironbuttrally.com/tech/aowprintout.cfm
If at all possible, carry what you plan to eat. Nothing like chowing down on a "looks OK" deli sandwich only to find out OK isn't operative. The "put them in the freezer" things do a good job of keeping food cooled. Wrapping your meals and keep-cool thing in a towel will do a good job of keeping meals at least cooled down. Don't ask my wife about what uncooled meatloaf sandwiches can do...
In the past, I've thought uncharitable thoughts about adding driving lights. No more. Doing 70 down US 301 at "oh-dark-thirty" I didn't find a young deer until "to late to swerve". If I'd stuck my foot out, I would have nailed the rascal. And probably vice versa. Although my FJR's LED headlights are bright, some added light would have given me options on that deer.
See above re: no detour options. If I was attempting any IBA ride, it would have been "movie over". Today (Sat.), between NW of Philadelphia and Christiana, DE, traffic looked like either rush hour hell, or Black Friday hell. I-95, 495, and 476 were locked up, the side routes I tried (PA routes in PA Delaware Cty) were locked up. It was a conspiracy to delay my ride long enough to put me in the path of significant rain. Again, because of the traffic, there were no options. An hour's ride took just short of two hours. End of attempt. (The weather took pity on me - only light rain the whole way home)