Mounting 2 pair of skis... help me decide

i skied on some 4frnt msp's last year, and the topsheet was messed up so i sent them back to 4frnt and got a brand new pair. i also got a huge discount on last years troublemakers from my cousin (brand new). the 4frnt's are a 161 and the tm's are a 175, and im right inbetween the two sizes, meaning the tm's are not too big and the 4frnt's are not too small.

i ski a lot of park, but also a lot of bumps. what should i use as a park ski and what should i use as my bump/ big mt. ski?
i was thinking that i would use my 4frnts as park skis and mount them maybe -1 from center, and then use my tm's as my bump and big mt ski. i dont know where to mount the tm's though, because i still wanna use them as a legit park ski sometimes.

thanks