I don't have a formula but I'm not sure that any hitch manufacturer knows exactly what receiver adapter we are going to put in or if it has a drop or not, but those things definitely put different leverages on the hitch receiver.
One thing I noticed when a friend used one of those adapters, he didn't have room to unhitch his trailer until the bike rack was removed as there wasn't enough room to raise the tongue off the ball without hitting the bike rack above it. That of course could depend on the double receiver adapter used and what the design of the bike rack or tongue locking mechanism might be.