Some time in the past I saw a picture of a forum members sling with five spoke bullitt style wheels on it. Who was it, what was the name of the wheel manufacturer, part number, style number?
IIRC, I have also seen pics of Bullit-style wheels on the Slingshot, but I can't remember where.
If you're willing to run different offsets compared to stock, 5-hole (5x114.3) Mustang wheels will fit the Slingshot. American Muscle has some affordably-priced Mustang wheels (https://www.americanmuscle.com…-mustang-wheels-rims.html). Newer wheels should also fit. 1994-2004 Mustang wheels are typically 30 mm offset for the front wheels and usually available in 8 or 9" widths. Rear wheels for the same years are typically 28 mm offset and run as wide as 10.5". The smaller offsets will generally place the wheels farther out for a wider stance and may also place the inner portion of the wheel closer to the suspension. WillTheyFit.com will allow you to input wheel and tire sizes, including offset to visualize the changes.
I have an American Muscle 10th Anniversary Cobra Style wheel 17x10.5 28mm Offse (currently on clearance for $120) with a 315/35ZR17 Nitto 555 G2 tire on the rear. That particular wheel has plenty of clearance around the brake rotor/caliper assembly, but I'm not sure if the 5-spoke Bullt-style wheels have the same clearance around the brake rotor/caliper assembly. I initially tried a 17x10.5" Bullit-style wheel from JEGS, but, IMO, it didn't have enough clearance around the brake rotor/caliper assembly so I returned it to JEGS.
AM also sells 5-spoke Bullit-style wheels for the 2005-2009 Mustang in 17-20" sizes, but maxes the width at 10".
It's easy to find various wheels whose diameter & width will fit the Slingshot, but finding wheels with the correct Offset is a PITA. It's much easier to buy a set of wheels from one of the Slingshot-specific vendors, but also more expensive.