Light Peak is located about one hour northeast of Lakeview, Oregon and features the Drake Peak Lookout that can be rented in summer. (Yes, Drake Peak Lookout is on the shoulder of Light Peak and not on Drake Peak...)
From Lakeview, Oregon take Oregon Highway 140 north toward Paisley. Following Hwy 140, turn right onto Hwy 140 east toward Adel. Turn left onto Forest Service (FS) Road 3615 traveling north about 6.8 miles, then right on FS Road 019. Continue on FS Road 019 about 5.3 miles to reach the turnoff to the Lookout and a good place to park for the 1/3 mile hike to the peak. The last few miles of FS 019 may be challenging or impossible in a passenger car - decent ground clearance is required. Note that there is a nice privy adjacent to the Lookout. Respect the space of any tenant.
In an high clearance vehicle for which you don't care about the paint you can get closer to the summit and perhaps even to the summit proper, but why not enjoy the walk? The summit is a bald with no trees or any easy way to support an antenna mast.
Note that a faint road just below the summit departs to the east to nearby Drake Peak W7O/CE-002. This is a cross-country route of about 3 miles RT that is recommended if you came all the way to do Light Peak. And vice versa.
It seems that both AT&T and T-mobile have some coverage up this way. I would not expect to work many on 2m FM in this area.
Somewhat near is Twelvemile Peak W7O/CE-006 that you may want to try - but it will be more challenging that Light or Drake.
