That looks to be an international Ranger so more of an F-150 than Ranger, also it will have a diesel engine not gasoline.
No matter what you do to the frame or anything else the legal towing limit comes from the VIN and Drivers Door sticker.
In some states you can get an engineers inspection and get upgraded weight limits but it is costly.
This is not a "can" you do it, of course you "can"
It is a "may" you do it, assuming you want to charge people for towing, then you need the legal "may" part to get a license.
So I would look up your '98's legal numbers, it is based on engine size and transmission, and then decide if it is worth the effort.