A class C will definitely get attention of local LEOs. The ones we encounter are generally resting during the day. Around Seattle, they are very aggressive to move stealth campers along. Many Walmarts are refusing to allow camping anywhere near large cities because they get lots of older sadly worn RVs trying to park form a long time and local ordinances do not allow camping.
Since you have never RVed before: How will you recharge batteries? Batteries will not last an extended time. Batteries are used for fridges controller/propane igniter, interior lights, fans, furnace fan heated by propane furnace. A generator will do that but the noise will get the attention of everyone and now no stealth camping. Solar panels work great for recharging but only in the sunshine and SF is notorious of lots of cloud covered days. Solar can be pricey and very obvious if not roof mounted. TV watchers - now you use more power and many antennas need to be raised - another red flag. Interior lights on inside at night = camping..........
Black water is not your only water issue - you will have grey water that is from shower/sink. ALL grey/black water is illegal to dump except at an approved dump site. Your fresh water tank will be a limiting factor as to how long before you need to dump and fill. Some campgrounds allow dumping for travelers for a fee. When staying in a campground it is included in the site fee.
A parked Class C in an urban area is a big red flag that someone is likely camping. A van is less obvious but will have VERY limited tank capacity. Vans have little on-board storage. You really need to get into several different types and think abut how the space would or would not work for you.
RV rentals are generally VERY expensive but might well be worth your time and expense to get a real life feel for the realities of rving.
Your dream sounds wonderful but please think this through carefully. Having to move every day would soon become a major chore. I know of no hotel that would allow you to camp in their parking lot from a liability standpoint alone......................... I wish you much luck in whatever you decide.