No in fact it's too much. If a 200 pound man wears a 40 pound vest that means he has overnight increased his walking weight by 20%. Would you suddenly slap 20% more weight on the bar over and above your max bench? How about 20% more weight on the bar with your max curl?
Yeah, I get it walking is different we are able to travel many miles while carrying stuff. But at the same time you don't need to go that heavy that fast. If I were you I would not wear anything heavier than a 20 pound vest. You will be surprised how much even 20 pounds picks up the heart rate. After a few weeks of this add an additional 5 pounds. Keep adding gradually. Your traps and hip flexors will thank you and you'll make some good cardio progress as well.