before making a decision you should at least pay for a load calculation to determine what type of system would be best.
There is a good chance you are right but a load test is cheap and accurate
what if you put in the window units and they run now stop?
or they only last 5 years and you got to buy new ones every 5 years?
on the onther hand
Maybe a split wont fit
or you will have to many upgrades to make it worth the cost
either way you should get your place sized up
good luck
I remember my first day,It was fun!