That's a tough one as there is no real direct route. Would you be comfortable pulling the trailer up the 74 out of palm desert? I'm guessing not so you're kind of stuck going around north.
But if you don't mind the 74 then 74 to 371 to 79 South
Take 79 south to Santa Ysabel then turn left (north) onto 78 to Julian.
To avoid the tight turns on the 74.
10 west to 215/15 South to Temecula.
Take the 79 South out of Temecula through Warner Springs until it ends at Santa Ysabel. Turn left (north) onto 78 to Julian.
The other straight route with a big climb is to go down to I8 west.
Take the S1 North (Sunrise Highway) until hwy 79 north to Julian.
Of the three choices I would say the route down the 10 through Warner Springs has the least amount of mountain driving. I pull my trailer in that area and the 78/79 is the way that most of the RVers go to Borrego which is on the other side of Julian from San Diego.
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2001 Suburban 4x4. 6.0L, 4.10 3/4 ton **** 2005 Jayco Jay Flight 27BH **** 1986 Coleman Columbia Popup
