I guess that's the price I pay for portability. Anything large enough to really stabilize it would be too heavy for me to carry, as well as a LOT more expensive. I picked up this G11 used for $200. It was in pretty sad condition, but a few $ and some tlc got it back to working condition. All the mounts I see that would be significantly more stable are at least $4k (even used!) and weigh a lot more.
sounds like you're getting an excellent return on investment there! You can get some nice views with the current setup and wait for an unexpected windfall or something for a bigger mount. There are some that break in half for easier transport.
Older Mountain Instruments MI-250's are extremely sturdy and come apart with a few screws into 2 pieces, that would easily handle a 6" f/12. You still need a heavy duty tripod. Did the older AP 900 mounts break into 2 pieces? Not sure but that would be another option.
The problem is that many of us want these older mounts with cheaper, simpler designs so they're hard to find on the used market. I have no need for any mount technology past the Astro-Physics QMD series or the older MI-250's.