Once in lower elevations, go south to I 10, and miss any sierra crossing.
I 10 takes you all the way. IN Texas or therabouts, can aim a little to the north to get to central Florida.
Yes yes and yes. I just told him the same thing.
80 West (south really, but...)
5 South
10 East
That is literally all the instruction needed to get to Florida on open safe freeways with the exception for getting onto the 80 in Tahoe.
I hope he listens.