So I finished the desert! I made some modifications to the entrance to the desert. After you enter the desert through the valley, you enter a cave that leads to the desert itself (the cave just above it). The path to the eastern desert is blocked by a gerudo guard that tells you that the path is blocked to unauthorized people, so you have to go to the fortress and talk to Abigail to get permission, maybe a letter saying: This kid has permission to enter the desert, like the letter that zelda gives you in ocarina of time.
The valley of death is still under works, but the Sheikah fortress and pillars need to be made tilewise. I don´t think there is tiles to make stone building/castle with roof?