The OP has a concurrently running post asking help to replace his split-rims. And again, five-bolt.
bolt circle pre-dates the most common vintage steel six lug “chevy truck wheel”. Any historians to clarify?
Late sixties airstream brochures tout their “Heavy Duty Truck Wheels" in their advertisement. I have a 1968
Chevy K10 Suburban with its original wheels that are absolutely identical to my airstream 15” six-lugs in every measurement, including zero offset, weight, and weld pattern. Neither say Kelsey-Hayes, but that’s what they are known to be.
If OP is desperate, maybe switch or drill drums to the most common six lugbolt pattern. Then have options from junkyards to Centerline Auto-Drags.
The OP hasn’t responded in a few days to either of his posts, so perhaps he is no longer desperate??
Pretty cool that the rivet spacing on Centerline Auto-Drags matches vintage airstream shell.
Pictured first is a six lug airstream wheel from the sixties that has "clips" to hold the somewhat rare and expensive today, older style ribbed edge baby moon hubcap.
The second image, mounted on 68 trailer is a seventies airstream steel wheel with "nubs" holding a jc whitney baby moon (so old, it's labeled "Made in Japan"). It appears that airstream never offered a moon cap for this later "nub" style wheel, It had a "full" wheel cover.