Tripods and heads are specified by the weight they will support . That's misleading, however. They further assume that whatever you support will be compact, symmetrical, and balanced over the tripod centerline, as extended objects tend to vibrate more. Obviously, your scope isn't what they have in mind. Therefore, the support you use should be vastly overrated for the weight of your equipment.
Vibration is the enemy in photography, digital or otherwise.
You can compensate for low light or subject motion, but if the camera vibrates during the exposure, the image is irreparably smeared. Remember that as you magnify an image in your scope, you also magnify the blurring effect of any vibrations. An inadequate support allows too much vibration, and the most expensive optics can't fix that. The compromise comes with field of view . In general, as magnification increases, field of view decreases.