Do note that the search light's range was a whopping 120. The highest sight range for any other unit is 91 for a vetted 222/251 with spotting scopes, and honestly those are borderline overpowered (and they cost significantly more and require a doctrinal upgrade on top of needing to be highly vetted). Range can go up for sure, but definitely nowhere near as high as 120.
It should be a lot closer to 120 than 70 as a starting sight range. If the team does go with the vet bonus route, you could have each vet level increase the range like DoomLord suggested.