Homeyba

I suppose you could ride east from SF to Davis then head south down the valley to Bakersfield. Then up to Tehachapi and over the pass on 202 to Lancaster/Palmdale. Then 138/18 E to Victorville. Between Mojave and Victorville/Apple Valley the terrain is pretty flat but it gets hilly as you head towards Yucca Valley then flat again through 29 palms on hwy 62. You're going to start running in to problems finding accommodations at intervals of 50 miles or less between 29 palms and Parker. I think it's between 80 and 100 miles and there is nothing (I mean nothing) out there. The terrain isn't bad but it is a pretty good haul. From Parker I'd take hwy95-72-60 to Wickenburg. That's another 80-100 mile pull and hwy 60 is all up hill, not steep but up hill. There is a rest stop about half way up hwy 60 so you can stop there. I think there is water there too but I don't remember for sure. You might be able to ride on I10. I've ridden on I10 between Indio and Blythe and it just plain sucks. There is a shoulder but constant barrage trucks and cars (24/7) flying by at 90mph... After Wickenburg it's a pretty short ride into Phoenix. I've ridden all of those rides at one time or another. If you start in San Diego it might be easier to avoid going more than 50 miles between stops.

Here is the thing about desert riding. Water is insanely important. Don't leave without enough water to get you where you are going. You can limp along without enough food but not water. You can die out there whether it's hot or not. If you are on roads between two towns you are going to have to deal with cars going insanely fast and buzzing by you. If you want a road with no cars you will be in the middle of nowhere going nowhere. The grades in the desert are generally very long and shallow. Not often will you see grades in excess of 6% except for short distances. It's not uncommon to be on 20+ miles grades of 1-3%. The time that you are talking about crossing the desert should be fine temperature wise but realize that at that time of year it can still get real hot or real cold and the wind is ever-present. If you want I can show you a picture of what the wind can be like out there.

As far as your speed goes, if you ride at 12mph you'll be on the bike less than 5hrs a day assuming you don't exceed 50miles. I think you're going to have to be open to some longer days, at least crossing the desert. Getting faster will definitely help because you will go slower with a load. You don't need to get up around 20mph but if you could get up to 15ish before you start I think you'll be in pretty good shape as long as you give yourself some recovery days along the way.