I rode the Rosarito-Ensenada ride a couple of times in the 1970s-'80s and it was mostly rollers, nothing too steep or long. Pretty much like my area in north central Texas. Strava will probably have some segments mapped out with reliable terrain/gradient estimates.
And, FWIW, the Mexicali-San Felipe ride on the Gulf coast side of Baja is pretty much pancake flat. Huge differences in terrain and economy from the Pacific coast side of Baja, at least back then. Haven't been back in decades though.