shoulder eyebolts and washers
Be sure to ask for galvanized (or stainless) shoulder eye bolts with washers. If by "wrapped around to make the eye" you mean something like the first picture, that will not do. You definitely want a shoulder eye bolt as seen in the second picture. You should be able to get them with large washers (something like 2 inches square and 3/16 inch thick) to help spread out the load on the sheet metal of your pickup bed. Each shoulder eye bolt should have 2 washers - one on top of the bed and one under the bed.
Besides marine supply stores, specialty tool and/or specialty supply stores can get them. I'm sure there are many places in you neck of woods that if they don't carry them, can get them in a day or two.