There aren't a lot of good nicknames for a one-syllable name. If you want a nickname, name him Trenton, and then Trent can be his nickname.
Famous people named Trent:
Musicians Trent Reznor, Trent Tomlinson, and Trent Willmon; football player Trent Edwards; U.S. Senator Trent Lott.
If your little Trent is into moving to Canada someday, he may want to attend Trent University in Peterborough, Ontario.