Justin Walker submitted this 500+ mile road route. For an FKT across the state any route would be allowed. Here's what Walker did:
Across the state of Oklahoma, from OK panhandle at the New Mexico border to the Arkansas border. Starting at the New Mexico border on E0200 Rd and proceeding east until highway 325. East on 325 to Boise City, merging onto US 412 east. Continue 412 east through Guymon to Woodward. From Woodward, taking 270 east, southeast through Seiling to highway 51 east, towards Canton. Continue 51 east through Canton, Okeene, Hennessey, Stillwater, Mannford and into Tulsa. In Tulsa, continue down Rt 66 or 11th street until it turns north to E 590 Rd or old Rt 33. Continue east on E 590 Rd through Inola to Choteau at US 69. Merge onto US 412 east again, at US 69 and continue until the Cherokee Turnpike. Then merge onto Alt 412 east (no pedestrians allowed on turnpikes). Continue east through Locust Grove, Rose, Leach and Kansas. Alt 412 then merges back onto US 412 east of Kansas, after the turnpike. Continue US 412 through West Siloam Springs, Oklahoma. The run terminates at the Arkansas border in Siloam Spring, Arkansas.