A significant improvement of the base used to keep the rod in place for my homemade dog toy modeled after The Happy Stick (Trademarked). This base slides over the pipe in the ground. The fiberglass rod with the female coupler on the end slides into the 3/4" X 3" pipe. Keep in mind that there is a weld bead on the inside of the pipe you will have to grind down to get the coupler to slide in. I'm spray painting mine now because it's already starting to rust. Gravity seems to keep it all in place at this point and I have not needed to figure out a way to keep it from all sliding apart.

3/4” fiberglass pole
https://mgs4u.com/product/34-od-round...

3/4” stainless steel couplings
https://mgs4u.com/product/stainless-s...