Good luck on your trip in March. You will be entering some beautiful country in Northern CA.
I know because I have driven that route many times. Our son graduated from HUMBOLDT STATE UNIVERSITY in ARCATA a couple years ago and I can't tell you how many times I have driven that route coming from our home here in Santa Ynez. As for a couple of Campgrounds you might enjoy: Check out BENBOW VALLEY RV RESORT & GOLF in Benbow CA (it is just south of Garberville)(www.benbowrv.com
). Another place is in ARCATA- MAD RIVER RAPIDS RV PARK (www.madriverrv.com
). Ofcourse there are several state parks also along that route. They are RICHARDSON GROVE SP & HUMBOLDT REDWOODS SP.
As for sights to see:
If you stay any lenght of time in one of the parks and you have a TOAD, I would recommend a drive through the route along 101 called the AVE OF THE GIANTS. I would not take a MH on this road but it is great with a TOAD. Some of these redwood trees are amazing.
The town of FERNDALE is interesting because of all the Restored Victorian Houses.
LOLETA has a Cheese Factory that is also a interesting tour. Both of these are just south of Eureka.
As for Route 101, from Willits to Eureka there are some sections that are only two lanes and can be narrow as the route passes through the two State Park areas. Also the logging trucks use 101 alot and these guys really move with huge logs or lumber loads. They mostly go southbound with the loads down to the mills in UKIAH. It is always fun when you catch one of these guys in the two lane sections
Weather in March can be great or it can be rainy. There is one section of HWY 101 that is noted for its mud / rock slides blocking 101. It is called the SUPERSITION HILL area. CAL TRANS has been re-working that area for years, so you might run into some construction delays.
Over all the route is very do-able. I have done it in a car and in my prior 30 ft MH (gasser). It is a very pretty drive and safe if you take your time carefully through the two lane sections. Other section are four lane divided roadway and are very easy to drive with easy grades up and down some of the hills.
Route 20 from WILLIAMS has a few issures that you should note. The CLEAR LAKE area has a couple of tight turns if you stay on ROUTE 20 which stays north of the lake. I believe truckers take the Route 53 to Route 29 cutoff which goes around the lake on the south side. In and around the CLEAR LAKE area you are not allowed to use your Exhaust brake.
There are also a couple of grades you will transverse just west of WILLIAMS. They are not hard but on the two lanes it might slow down just a bit.
As for north of Arcata, I am not really that familar with what is up there. I have done a day trip to the PATRICKS POINT SP. It is a very nice park that has trails along the coast line. Ofcourse further up is the REDWOOD NATIONAL PARK. We never managed to get up there with all the times we went to see our son at college but I guess we will just have to head up there some time on the future as one of our vacation trips.
I hope this helps and there are many more things to see and do up along CA North Coast into OREGON. Good Luck, drive safe and take some great pic's.