Thanks for the info, it's a shame that SRAM doesn't make anything longer. The bike came with a Shimano Deore drivetrain, and that took up the slack no problem, but the distance between the pulleys on the Deore RD is about 99 mm instead of SRAM's 93mm, so once the chain is double-backed on itself, the Deore takes up about 12mm more chain, which is sufficient. However, I prefer using the grip shifts that I have for the SRAM RD much more than the Deore's triggers, so I'm going to stick with SRAM here.

I certainly plan to avoid the small-small combo, but in fact it is not so necessary to do so on the big dummy because it has super-long chainstays of 83 cm, or 33 inches, (it's a cargo bike with an extended rear end, a massive integrated rack and huge bags) so the deflection in any part of the chain is pretty minimal even with extreme cross-chaining - so this is one instance where cross-chaining should be OK.

BTW - I love the Big Dummy, and in my first 10 days of having it I've already been using it to haul stuff way more often than I expected, plus it makes me so happy to ride it and show off my huge beast