(from reddit)
(1) 그것만 해도 괜찮아요 – That alone will suffice.
(2) 빚만 해도 100만원이 넘어요 – The debt alone is more than a million won.
(3) 지금 가진 자산만 해도 그는 제일 부자에요. – His current asset alone makes him the richest person.

Previous sentence with a topic. Then in the subsequent sentence following the previous sentence, (noun) + 만 해도 means “(noun) taken as an example”

(1) 요즘 감기가 유행이에요. 우리 가족만 해도 다 감기에 걸렸어요. It’s the flu season. All my family, taken as an example, have caught the flu.
(2) 일자리 구하기가 힘들어요. 내 친구들만 해도 아무도 일자리가 없어요. It’s hard to get a job these days. None of my friends, taken as an example, have a job.

(Past time noun) + 만 해도 is a contraction of -까지만 해도 means “At/Until/Even (time noun)” and implies the situation used to be different from today.

(1) 저희 때는 한 반에 50명 정도가 있었어요 – In my days, there were about 50 students in a class (No implication. The sentence straightforwardly states there used to be 50 students per class during her time.)
(2) 저희 때도 한 반에 50명 정도가 있었어요 – In my days, there were about 50 student in a class, as well. (Implies that the situation is the same today, that there are 50 students per class during her time as well as today.)
(3) 저희 때만 해도 한 반에 50명 정도가 있어어요. – In my days, there were about 50 student in a class (Implies the situation is different, that there used to be 50 students per class during her time, but there are different number of students per class today.)