If you're heading up from the Valley on the way to CR and water is scarce, instead of going up from the CR x JMT junction there at Sunrise Creek, another way to do it is to keep going up the JMT a couple miles to the Forsyth Trail, water up at Sunrise Creek right there, enjoy a lesser climb, hit the junction of the Sunrise Trail and head right to the creek if you need more, then make your way up to CR, approaching from the north instead of the south. Camping at the summit of CR is technically illegal (and not really appreciated by others), but especially if lightning is an issue, the flats on the north side toward the edge of Tenaya Canyon are safer, with not only better/legal sites and lower ground, but with trees that are just the right height as recommended for shelter during a storm.
As for fires: a wink and a nod from one person doesn't necessarily translate into not getting a citation from an LE ranger. Those downed and sectioned trees are part of maintenance, not necessarily for your burning convenience. They usually won't have a problem with you burning them in normal times, but if there's a sign that says "No Fires", you pretty much have to take that as the deal, and assume that if you're the only site with flames rising up from your pit, it's going to draw the unwanted attention of someone that has a ticket book.