Yes I will go prepared with Camera, compass, altimeter, and perhaps a S&W as there have been some Cougars spotted in the area ! It's been a very wet winter around these parts so I might need a 4 wheel drive and a come a long which I always carry when I'm out in the woods. My wife will not be happy if I take her 4 wheel drive Honda so I'm stuck with my 2 wheel drive Ranger. I'm pretty sure my friend has a 4 wheel drive PU. It might be a few weeks but I'll report back ASAP. Yes elevation is on the top of my list.
I neglected to mention earlier that if you have a hand-held GPS that has a read-out for the coordinates, you can probably also use it to determine the altitude of the placard find location. The GPS and altimeter read-outs can be compared, but I consider the GPS altitude indication to be more accurate based on my personal experience with different hand-held GPS instruments.
BTW, just for interest sake, the listed USGS elevations for surrounding locations are:
Silver Lake: Mean Water Elevation, 158 m (518 ft)
Castle Rock: Elevation, 14.9 m (49-56 ft) rock edifice: 190 ft
Toutle: Elevation, 152 m (499 ft)