It's not uncommon to do a case report following/during a sub-I. A lot of times this starts with an interesting case that the student offers to write up and the attending accepts. Honestly the value of a case report is pretty small overall, but doing this may make a good impression on the program at which you are rotating. Would necessarily recommend it, but it doesn't hurt. Doing real research in 1 month while working 80-100 hours a week is essentially impossible.