It is doable, but most cadets won't do it because at least for AFROTC, it can impact you when you go for a board. Boards will use your rank in the unit for the OML. If you are overseas, you are not going to have a job in the unit, no job and you are less competitive, which means you may not have an OML high enough to get SFT. Don't get SFT and you will not be commissioned into the AF.
That board occurs your soph. yr., spring semester. Hence, your fall semester is going to be important to be at your school. If selected for SFT, you need to be at the school because you will need to get medical issues done and do what is called a bag drag. Hard to do overseas.
Your jr yr spring semester is going to be important because it is the last time before you meet your career board in the fall of your sr yr. Hence, again you will want to be at your school so you can have a job.
As you can see there are going to be limited times that won't risk or jeopardize your career in ROTC.
As I said it is doable, but you will need to time it out. I know our DS's friend did it, and I believe they did spring jr yr. (Only this yr did they push career assignments to sr yr, prior to that it was spring jr yr)
Honestly, you will see the world with the military. We lived in the UK for 3 yrs, on top of that Bullet did TDY's to Germany, Belgium, Spain, Turkey, Korea, Qatar, and Iraq. That was on top of living in CA, NM, ID, NC, AK, KS and VA.