Summary - The hike (at least from the north) through the burn area is a sufferfest of deep, continuous treefall, exposure, and route finding. The trail is mostly gone and you must have a GPS and map or be very good with compass and map to avoid missing several crucial turns. As with most summits in this area, plan on HF to activate unless you know there are other SOTA ops in the area. Bottom line: skip this one, at least from the northern trailhead.
TL;DR - Driving down for the 2023 W7O camp out, I hoped to do four hills along route 138, including Rattlesnake Mountain. Maps show a 2.5 mile trail that climbs 1200 feet at the end of a 13 mile forest road drive. The driving part is fairly easy: turn off 138 at FR37 (43° 13.65, 122° 23.64), follow FR37 then FR37025 to the trailhead. The trail is easy to follow for the first quarter mile before the burn. From this point, it is a different story: you will be climbing and route finding through thick and continous debris from the fire for most of the hike and it is slow going.
A bit before the mile mark you encounter the first knife-edge ridge, stay high and on the west side. At 1.6 miles (43° 6.7939' 122° 24.7397), the ridge climbs steeply. The way around is to the east. The path is visible here, do not miss it or you will be driven down the steep slope, which is very difficult to get back up. Even staying on the path, the way here is challenging. After getting around the high point, you'll reach the nose of the summit ridge; follow the ridge to the top.
The summit itself is open meadow and manzanita with nice views of the surrounding hills. Be very careful, the western side has both quite the view and quite the drop! There are trees and places to strap a mast There are also mosquitoes. Lots and lots of mosquitoes. Given the location, two meter contacts are difficult, so HF is a must.
This was one of those first activations where the mantra, it's probably okay after I get through this part wasn't true except for the sitting-on-the-summit section. The five miles of route finding and tree fall negotiating turned an under two hour hike into the three hour plus sufferfest. As I noted in the summary, I'd skip this one and spend my day on other, more accessible peaks in the area.