I echo AK5SD's comments. Don't go thru the gate but park in nearby areas at the gate. This road is frequented by fire crews and other Rangers who may be only visiting the lookout for a few minutes. Don't get caught behind a locked gate! And the lookout road is mostly a one-way which would create problems if you met traffic. It's only about a mile hike (750 ft elev gain) from the gate to the lookout.
The weekday lookout Ranger is Shannon, an eight yr veteran of this lookout. Very nice lady. As the sign near the sanican and the bottom of the stairs, make sure to callout/announce your arrival. Do not hike up un-announced...it's not courteous, esp. mid-week when there is infrequent visitor traffic. Shannon is somewhat a health nut...bring her some fresh fruit! If the lookout shutters are open, the lookout is staffed. Shannon said the lookout is generally operational May-Sept.
Not wanting to interfere with the lookout radios and after asking permission to activate, I setup my crappie pole & LNR EFHW on a rock outcropping about 50 yds south of the lookout. Great vistas. Verizon cell coverage was about 2-3 bars. It can be windy here. Good coverage of the Mt. Bachelor repeator, K7ZM, on 145.45- (103.5) and the WA7TYD Sunriver on 146.64-. Other central Oregon repeators can be seen at https://goo.gl/fy1XL6 .