Hi Lawrence
The Caravan Club's "Caravan Europe" (2006 says of the Julier Pass.
"Height above sea Level 2284m (7493 feet). Min width road 4m, Max vehicle width 2.5. Well engineered road appraoched from Chur, via Sils, Fine scenery. Negotiable by caravans from N to S. Alternative rail tunnel from Thussi to Samedan."
As North to South is best you could try the that easier way on the way "down" and consider if you want to return that way too.
Having said that I would recommend the Gotthand Tunnel/Pass for Camping La Riva but note the warning in my review that the West side of the lake road is NOT good for towing, VERY NARROW, particularly in some of the villages enroute.
Best wishes for a happy hol.
Tim