I'm all for experimentation, however I fail to enjoy reinventing the wheel....It hasn't been many years ago that I fell in love with the .204 cartridge with it's flat trajectory and terminal effects on Varmints...
Shortly afterwards I had a custom AR upper built in .223 with a slow twist rifling (1/14) to allow me to push the 40 gr V-Max at near .204 velocities and thought, conversely, that if I could achieve good results with that combination, moving down the a 35gr V-Max should be even better...In the end, the lighter weight had even more draw backs than the 40gr in the .223....It had the same flat trajectory, but as the distance increased past 300 yards, the stability of the bullet diminished, especially of any breeze (not wind) happened to show itself...
My 6.5 CM, using Hornaty factory 120 gr V-Max bullets produces velocities of 2930 fps as claimed by the manufacturer and at 100 yards produces excellent accuracy..From reports I have read in the past...going to the 123 and 142gr bullet, with the right powder charge, should be excellent long distance performers due to the much higher Ballistic Coefficient factor that is achieved due to the longer bearing surface...
I'm afraid that by shifting to a shorter/lighter bullet (below what's available), you will be sorely disappointed in your anticipated results...as well as negating the potential terminal effects when used against any kind of game...