Actually only the dropout tips are in contact with scale center. You just can't see that in photo.

I then read the OP again and acknowledged the difference between BOB and Burley at my second post. Was not recommending a BOB. They are not intended for children. Just giving the OP a general idea of how he can weigh the load bearing on his rear wheel with whatever trailer he chooses. Bath scale was suggested by fietsbob. I don't have a Burley on hand for a photo op, so I used my BOB for a substitute. Yes, a Burley will be a minimal load compared to a BOB.

Yes, this thread is about a child trailer. I think I'll delete both posts as they really don't apply to this discussion. They were more about "heavy loads on wheelsets". Thanks for catching that, Greg.