One could always take the tires off, get the rims blasted and powder coated to match the rig.
Then dont pay them.And if the shop that does the powdercoating does not do it properly the coating will not flow into that crevice properly to seal it good.
When you get your next set just pump your bearing buddys until you blow the seal and you will have a nice rust preventative coating of grease over the entire wheel.
You can't find car wheels, aluminum or otherwise with no offset. Rear wheel drive cars have wheels with the centers offset to the inside. Front wheel drives are offset to the outside. Not only is there a bolt pattern issue but there is a metric/SAE consideration as well. Your boat trailer has an SAE bolt pattern (4, 4-1/2, 4-3/4, 5 inch bolt circle etc). Many autos made in recent years have gone to a metric bolt circle. While the difference may be slight, it is not a perfect fit and the lugs will loosen. Then there is the issue of the taper on the lug nuts. So unless you know what you are doing, swapping wheels is not as simple as it used to be.