Nighthawk rings, counterweight, dovetail plate?

Is this single mounting ring included with a Stellarvue Nighthawk sufficient, or should I be picking up a second ring for dovetail attachment?

This scope is also going to be riding on a lxd55 mount. Suggestions on what size of counterweight to look for, and where to find it? My mount already has a 10 lb. with it, but that might just be over kill...it'd be nice to have a smaller weight for transportation purposes.

Lastly, any suggestions for a dovetail plate? Cheaper the better, as far as I'm concerned....

Thanks guys!