(I will assume you have already followed the hack above and obtained unlimited universal stripes, otherwise it is hard to search for the mercenary's XP number)
After some days of testing, I believe that your actual gear score (the score without editing the level) determines whether you succeed or fail at an expedition level. So, if you want to complete more levels by editing levels, make sure NOT to edit the negative XP mercenary to 60/60 (because the negative XP mercenary is always at level 1 when the server checks your real gear score). Instead, scroll up (or down) on the "view" page and find the number 7700 (= level 20)/17700 (= level 30)/ ???? (some other numbers if mercenary is not level 20 or 30), this is some other mercenary's XP. Edit this number to 192700.
After adjusting the XP, scroll down past three large numbers. The level cap is located two rows below the fourth large number (directly under the row that shows number "1"). You can then set that number (0 = level 20, 10 = level 30, etc.) to 40 (which equals level 60, the max level). This is basically the same as what is shown in the video, except you don't need to change "-1" to "0".
Then, go to the expedition and use "autosquad" (which gives you the highest gear score) get your highest gear score mercenaries. Usually you will be able to progress 1 or 2 more levels.
You can always try editing mercenary's level after leveling up the minivan or mercenaries, as this boosts your real gear score.