I tried adding a 3-drawer middle chest to my old Craftsman top and bottom box combo, and I had exactly that same problem. It raised the top chest so high I could not see into it and it was difficult to reach tools in the top of the top chest or in the top 2 drawers. And I am 6"2" tall.
I returned the middle chest and later on I bought the Craftsman wider top and bottom combo, I think it is 38 inches wide and the bottom drawers are 22 inches on the bottom chest and 18 inches on the top chest. Even so, I would like to have a side cabinet on mine too. I could use the extra room.
I would say get the side chest. It will probably work out a lot better for you, and have mofres storage space too.