41 is OK, but your main problem is that Potwisha campground is on 198, and 198 is not a road for large vehicles.
https://www.nps.gov/seki/planyourvisit/vehicle-restrictions.htm
Even if you came into Sequoia NP on 180 (out of Fresno), you'd still have to take 198 between Giant Forest down to Potwisha. Is there a particular reason you need to camp at Potwisha? Are you going to the parks now? If so, check the park website (the best source of information for any national park) for campground status; at that end of the park, Lodgepole is open, but I think that Dorst is closed.
