I've mounted a scope to a tripod before as part of just comparing it to other scopes, used some photography gear (arca plate, screw stud and super clamp) and was able to securely mount the scope so that I could point it at whatever I needed.
What I can tell you is that using a scope as a spotting scope would suck. The eye relief and eye box being well off the back of the scope make it very difficult to hold your head in the correct position to view through the scope. You're basically hovering in mid-air about 3-4 inches back off the scope with a tight viewing window. Without a rifle stock and cheek piece to stabilize your position it's very difficult.
I'd just pick up a spotting scope instead... much simpler.