'I am surprised these small dimensional changes made such a difference in handling, but I am a believer.'

Trail and rake are usu measured in millimeters in the bike world, Wound Up, a high end fork company, offers their road and triathlon forks in 2 different rake options: 38 and 43mm. so a difference of a couple of mm can make one bike feel completely different from another, if all other things are the same. Tire size and pressure have a lot to do with it as well, but the more major differences on your bike would be to put the right size fork/wheel on the front.

With rake and trail on a chopper bike like on the chunk site can be measure more grossly. But those are true hacks. Subtle differences work on high end precision machines. ballparks work great on hacks, esp when you are very tolerant of the results. I think you are better off replacing the front wheel and fork. Have fun building out other things on the bike. Make it into a tricycle- no worries of falling over when a little tipsy!

With tires, more or less, you want wider tires than 1 1/4" out there, esp later in the week when the playa becomes layered with dust concealing the potholes and slots. I have seen plenty of of 10 speeds and even a few fixies out there, but I wouldn't do it unless you have really amazing bike skills and know your machine well. The minimum width I would start is 1.5 or 1 1/2" wide, which precludes most road bikes and hybrids. A narrower tire is faster, but burning man is not a race- it's too hot in the day for expending that much energy and at night there are too many darkwads stepping in your path. Max you'll be going is 6-10 mph, unless you are riding intercept, where you need to be just a little faster than the artcars who are supposed to be traveling at 5mph max.

At Black Rock City, a bike is the fastest mode of transport.