I don't think 54 is maxed,,, with another mine boost somewhere and better strafing, and a good Trev, I should be able to save enough time to cut the time down to 53. I will be trying for this time in my second "good copy" TAS of the game, whenever that may be. I still have to finish this first one.
52 is a humonguous strech, and 51 is likely impossible, as Goose stated earlier.