At lvl 46 you start getting 5 free sayhas (<75 version) per lvl from growth missions.
So you really just need to leapfrog 40-46, which can happen with 1-2 decent magic lamp hits during the first lvl 40 transcendant. Especially if you go in with a gust activated before your sayha burns out, and the free 100% lamp flame from the lvl 40 quest.
I've run multiple alts to lvl 40 to lvl up personal clan 5k fame, and always just jump right into transcendant after hitting 40. Some of them only get out at 43-45 , but others come out at lvl 49+ if you get lucky on the first lamps and get to 46 in time to reapply the free sayhas early in the dungon run.
Worst cases, can just get to 40, pop the 100% flame and run the dungon with at least a gust, then log out the alt till tomorrow, log back in with 40+ mins left on the 100% flame. Have received the free daily sayha top up and use it to reapply a new gust and do the 2nd run. You will almost certainly finish the 2nd days run over 51 with some extra free (<75)sayha banked.
(Log out and wait for a 3rd/4th day if you really want to get the most value from that 100% flame buff)
Can also do this with multiple chars on same acct and have them acct share gusts to the main char on that acct if required.