Never underestimate what you can bring to the table Martin! A good tip we received from many was to cross at Tecate border for ease. Stay at Potrero RV Campground ($38/night) two or three days prior and then walk over from USA side in advance to get your necessary permits/insurance etc, so easy to cross over with RV on day crossing. When comfortable you can boondock many places USA side prior to actual crossing day.
FYI: Tel cel sim cards work well and are readily available at OXXO stores. Calimax for groceries - be careful what you cross border with food/alcohol wise. Check beforehand what's permissible, and stock up here as soon as you cross.
If for any reason you struggle to create a group for the same time you need, ask others held up at Potrero, there waiting to cross if they'd mind if you just joined them to get deep into the Baja the first few days. You'll pick up quite a bit of knowledge just talking to folks in that CG alone that are returning or going down for their "umpteenth" trip.
Most advise to cross border early in the morning and try to get quite a bit south away from the border towns. For comfort and safety, DO NOT drive at night on the highway = cattle roam and other reasons.
Go enjoy, and take your time - everything in Mexico is mañana