Re: Just starting out, but addicted already!
I've tinkered with a several trailer builds I have to reccomend looking on craigslist or thrift stores for a schwinn or simular trailer used to haul kids around take the fabric off and mount the biggest plastic truck box wal-mart sells it fit perfectly and the wide girth and tall 20 inch tires make it very stable esp with the proper trailer hitch attatchment. I had used a 2 wheel dolly but that thing was kinda dangerous liked to flip and take me with it put a nice bruise in my gut when the handlebar jabbed me (it's a 1972 schwinn road bike real iron horse handlebars flipped)
Only problem I see with the shift kit is the federal law limits us to 30 mph. I'd gear it low as possible to have low end torq 30 mph is plenty fast on a bike and worth the no insurance no license requirement.