The best cruising guide is Shawn Breeding & Heather Bansmer's "Sea of Cortez" - a cruiser's guidebook. It is targeted towards cruising - not trailering however.
We trailered Passage Weaver (R-27) down on the mainland side - to San Carlos , Sonora in March this year. The roads are pretty good - better than the ones in California. You will need an import permit for the boat (good for 10 years I think?). Vagabundos ( a Baja travelling resource / club) are a great resource for permits, insurance, etc.
I don't know if there are any good launch ramps, or rig storage places on Baja. That's why we went down the Mainland side. There must be, perhaps Vagabundos could help since lots of their members trailer their fishing boats down. We may learn more this winter - we're taking our camper down to Cabo in February.
We launched at San Carlos Marina - an excellent facility, and great safe dry storage at Marina Seca. We waited for a weather window (winds) to cross over to Santa Rosalia (80 mile crossing). When we arrived, we discovered the Marina did not have fuel - they had not paid their Pemex bill. We think Escondido did not have fuel either. Had to fill using borrowed jerry cans & hiking to the gas station. It was a pain...as a result we did not try to run down to La Paz and stayed around the Concepcion area...
Mac & Linda