Rolling for seven hours is not even that hard. I don't usually roll for less than 7 hours, and if I did that would suck. What I usually do is just take your first pill whenever you see best, then take the second one about 1.5hours later. If they are good pokeballs or mints, you should be set for 7 hours... at least I always am. I've rolled 9 hours before, but that was off of 3 pills, which I will never do again, because I spaced them out terribly (one every 2-2.5 hours, I didn't know as much as I do now about mdma).
Good luck! It is easily possible. Don't understand people on this board who roll for like 3 hours and think thats normal....It is so much about the environment too, be around people you like, and do tricks with each other to intensify and increase the duration of the roll. Nothing blows me up more than finding a girl with an amazing smile and just spending time with her (at raves of course).