There are a lot of variables to consider. As an example, I have a 1000lb Gannon roll-over that is 81" wide. There are times when my 12,000lb 75hp tractor will not pull it. Should I get lighter duty implements because there are times when my tractor won't handle it? There are 8' wide boxes out there that are called heavy duty and weigh less than 600lbs. My 66" wide Gannon roll-over that I use behind my 32hp tractor is about 700lbs and I have the same exact problem with it. There are conditions when it will stop the tractor. Should I have lighter duty boxes for both of my tractors?, NO, I just raise the box a little and go on or use Draft Control and not even worry about it. I can pretty much say that if I had lighter duty implements, most of them would be on the scrap pile.
But all of this is up to each individual, all any of us can do is suggest what has and has not worked for them or others that they know of.