I'm retired so everything is reasonably convenient for me :-) I don't think there is a concept such as "unreasonably convenient" because if it was unreasonably, it wouldn't be convenient. I think the opposite of "reasonably convenient" would be "unreasonably inconvenient."

Unreasonably convenient would be if you had to do too much rescheduling of your own schedule to make her schedule work. I'm picking up the grandchildren in an hour so daughter-in-law can work; if I suddenly wanted to change days (they are off all week for Spring break from school) my daughter-in-law would have to call her work and clients and reschedule all them and see if they were available for the new day, etc.; some of them might not be. Anything that would cause a domino effect in scheduling on your part would be unreasonable. But, if it is just you and you don't mind, then that's reasonably convenient.