I just did a challenge from here to get "santoblasted" in an early loop. Managed to get santoblasted on loop 6, and believe it is quite possible to do as early as loop 5. So I'm sure you surely can get to the quarry and back in loop 7. I got to the dam on my first try, loop 5, but too late to cross it. You just need to install the water machine in the rover, get the stuff from the lost rover, charge up and go to get to the dam, at least, on the first attempt.
The reason why you can't get to Santorini on the first attempt is less because of resources, and more because even if you have enough it blows up before you get all the way. You'll need the code so you can cross the dam earlier first either way. edit: yeah, I was probably wrong there. I'm not strictly sure if it is possible or not to get to Santorini in time if you cross the river just as the dam closes, but I agree and believe that you could get just short of Santorini even if there is enough time.