It is quite safe and bearable to do a Baja trip in July -August,personally done it, with certain caveats , and the KLR is the ideal vehicle.
There is no need to believe that you will have to seek out dirt roads in order to get away from hordes of motorhomes and campers clogging the highways. They just are not there in any significant numbers. The highways are always very thinly travelled once you get south of Ensenada. Winter is the favoured time for these snowbirds to flock to Baja and even then they are few and far between on the roads, they migrate to their selected little beach spots and stay put.
If you go in July-August you will find that temperatures along the Pacific coast along Mex 1 are very nice because of the wind coming from the west off the cold water of the ocean currents. This is the case from Tijuana to El Rosario . But then the highway goes inland and into desert mountains and the temp will shoot up until you get back to the coast plains and to Guerrero Negro in Baja Cal. Sur. From there it is eastward again all the way to the Sea of Cortez and down to Los Cabos where it is always very hot in summer, figure on 40 to 45C in the middle of the day. Also expect very hot if you come down Mex 5 from Mexicali to San Felipe. Nice riding weather if you stick to pavement though.
Dress appropriately ,loose fitting light coloured ,a mesh jacket and pants are ideal.If this is your first ever trip to Baja it might be worth considering sticking to pavement most of the time and to seek out the odd bit of well groomed gravel road only in the areas where the temperatures are in the lower range i.e. west side . I would not think that you would want to be riding alone along some of the dirt and gravel backroads in the torrid zones lest a tumble, a mechanical breakdown, or dry fuel tank should strand you or hyperthermia due to all the exertion sets in on you without you catching its warning signs.
You will be in the season when sudden intense thunderstorms can boil up over the desert in the afternoon and they could easily maroon you in the middle of nowhere if they dump a load of water that washes out a section of your trail or turns it into a mudhole for some time.Hurricanes are also a possibility , and they can wash out roads and bridges. But if you stay on the main roads you will at least be able to get out and road repairs and detours will be arranged much more quickly.
You can certainly camp out if you wish, pick an isolated spot out of view or some of the supervised beaches ,official campgrounds or rent a spot and a palm covered site at one of the empty RV campgrounds. But do you really want to swelter through a 36C night in a tent on a muggy insect ridden beach?There are lots of inexpensive motels with a fan or ac, prices will be lower than during the winter peak season.Enjoy the trip.