OOS is not a problem at all. Both of mine went Greek - guys easier than girls (only due to the number of girls that know each other & the recruitment format) but both did fine. Both were in leadership within the Greek system & in other groups.
It really is true - once you enroll everyone is an Aggie first. There is an activity fair with hundreds of clubs/organizations shortly after school starts in the fall. TAMU seems smaller the more opportunities you take advantage of - just get involved. My kids loved it there! The huge plus with the size of the school is the clubs are so varied & plentiful, so you can find your niche fairly easily.
Fish camp - there is you tube video on Fish Camp - CC won’t allow the link, but just google it. It really is a wonderful source of information and contacts. Small groups get together during the first couple weeks of school too - so you have a group that will be there from the first day on campus. Camp counselors are involved in other groups too - some will be Greeks, so that is another plus. Impact is basically the same as Fish Camp but with more religious focus. Sign ups fill up for both programs. They actually are camps – not on campus, the buses leave from TAMU & take you to the camps. TAMU has a TON of traditions & this is a great way to learn them as well as meet some other freshmen before school starts.