So I have the Berlebach Planet tripod, and the DM6 mount with the 8" extension. At some point I will attempt to mount a 7" refractor on it and see how it goes. (If it doesnt work I'll go for the Losmandy HD tripod).
I know one possibility is that I can drill holes in the tripod, raise the spreader a couple of inches, and use the 50cm tray (or continue using the 37cm one in the new, higher position). This has been discussed in a recent thread. It would widen the legs and thus apparently help with the "moment arm" effect of using a relatively large refractor with the Planet.
I came up with another possible solution that I want to propose here and see if anyone thinks it might work, or is a bad idea for some reason. Instead of moving the spreader and widening the legs, I could put a 10 pound weight right above each foot of the tripod. This makes the tripod much less top-heavy, and much less "tippy". I have one such weight and have experimented with it above one of the feet (see below), it's very securely attached with no chance of slippage and it seems very promising. I also think the damping time will be extremely low. With two more weights on the other feet, it will make the tripod so heavy and stable that it will become kinda pier-like, I think.
What I don't know, though, is if this solution might eliminate the moment arm effect. I'm no physicist. Of course I can try it myself when the time comes, and see how stable it appears. But still, I wonder if it's a bad idea for some reason and if I really should be widening the legs. (Besides not trusting myself to do a solid spreader re-installation job, I also don't have much space and so the Planet in its normal, unwidened state is good for me... unless I really need to be widening the legs and thats the end of the story!) I suppose what I'm asking is, if it turns out that it seems very stable to me with my proposed solution, then is it stable? Or am I missing something about the reality of "moment arm" and the degree of spread of the legs of a tripod, regardless of how heavy it is and stable it seems? Thanks for any thoughts.....