Gravel foundation question

Quick question, so I’m building a 12x16 shed on gravel. Going with a gravel depth of 6”. Using 4”x8” treated wood. We still need to do landscape in the yard where the shed is going so I’ll be looking at having roughly 3-4” above ground meaning the trench the wood frame sits in will only be 3.5” deep. Will that be deep enough to hold everything together? Thanks