I-5 Northbound from Los Angeles to Paso Robles

I've gone that route more times than I can count in both directions with Chevy C3500 pulling a 38 ft 5th wheel (15,000lbs). Going downhill from Gorman there are truck lane and speed restrictions. If you have an exhaust brake it helps tremendously. If no exhaust brake then you need to use what is known as "Aggressive Braking Technique" Use the same gear or lower that you used to climb the hill (I had to use first gear with my truck). My top speed in first was 30MPH so I would only allow the speed to get to 25MPH and then I would use the truck and trailer brakes hard for a few seconds to drop the speed back to 20MPH. Make sure no one is following too close. Let the speed creep up again to 25MPH and then brake again for a few seconds to drop to 20MPH. Keep doing this all the way down the hill to save your brakes.

It's kind of a boring drive along I-5 with not much to see along the way. I actually prefer to go Hwy 101 when headed to Paso Robles area. More to see along the way. It's a good route with only a few hills.

Here is a conditions map with up dates. I'm not a big fan of the Grapevine route......Conditions >>>>LINK

Take Bear II's advice and go 101.

X2 on what the bear 11 said

I would take US Hwy 101 as more scenic but I don't avoid going either direction on I5 over the Grapevine. El Paso de Robles might get chilly. Think about staying on the coast where its warmer, say Hearst San Simeon SP, and drive over to Paso on CA Hwy 41 or 46. Gee, trying to remember any pleasant weather at Army Camp Roberts when stationed there....nope...no memory of pleasant weather.

I would take 101.

Used it many times with out TT and our 5th wheel. No problem unless it snows.

If you want to get there quick, take I-5. If you're prefer to take your time and want a scenic route... take 101..

Family used to haul our 1949 Airstream with a '72 Toyota Landcruiser J50.. family of 5 and all our stuff. 35mph in 2nd gear all the way up, usually a truck or two to hang with.

Modern vehicle, well matched (sound like you have a capable rig) no problem.

X what Bear wrote. Drive that way at least 5x a year with the rig visiting friends, even more often when the kids went to SacState. It's a nice road, it is an easy drive...it is not a fun drive. The ups are long as are the downs. Just watch your speed carefully, don't rush, and all will be fine: I assume your truck is in good condition.
If you are not in a rush, highway 101 is an easier, leveler, but possibly slower drive due to traffic. Take the 118 through Simi and it becomes the 23 as it turns through Thousand Oaks. It meets the 101 and you drive through traffic in Oxnard. The drive takes you on the freeway through Ventura and Santa Barbara, very scenic, but it can be congested in Santa Barbara. Then wide open again with one short climb heading into Beulton. If your making a long trip of it an overnight at Flying Flags in Beulton is great, and the little gray shack type restaurant on the corner is historic and great. Then on to Paso. Even if you can't make a long trip of it, the 101 is an easier drive. Happy Trails.

Kaly, you bet! The 118 is a nice country drive.

If traffic or weather cause concern take the 126 from 5 to 101. just a couple stop lights just as you get on 126 then a couple more in two towns you go through. Mostly 4 lanes all the way. Only big uphill is the Cuesta Grade. Hwy. 41 between Atascadero and Morro Bay is closed due to a landslide until at least the middle of February.