tom mctevia , 42 , and his passenger and best friend , tina hoisington , 45 , died after their atv plunged from an idaho overlook on sunday .
witnesses said they got too close to the edge while posing for a photo .
mctevia was left paralyzed in another atv accident 11 years earlier .
but the former cop and navy veteran continued to stay active and advocated for better trails for people in wheelchairs .