I don't recommend wheel adaptors either...spacers slip over the studs, generally giving 1/4." "Adaptors" bolt on and may or may not change the bolt pattern as well.
They do add extra stress to the wheel studs and front end components. There is also the inconvenience/ safety factor, every time you have a wheel off for service, it needs to be re-torqued after approx 80 miles, and should be rechecked again after every wheeling excursion. Now think that you have two sets of lugs on every corner now, and that you have to remove the wheel everytime you need to torque the adaptors, and then torque and re-torque the wheels again.
Most people can't be bothered... I have seen the aftermath of an adaptor coming off... not pretty.
Try finding a wheel with the backspacing you need to achieve the look you are after, most aftermarket 15" wheels have a 3.75" backspace, most factory Ford 15" wheels from about 1980 and up have either 3.25 or 3.5" backspace and are only 7- 7 1/4" wide. An aftermarket 8 or 10" wide wheel with 3.75" of b.s. will push the outside of the wheel out 4.25- 6.25", vs. the factory wheels 3.5"