Triangle from the mount and overhooking butterfly guard is money.
Also, you can hit a triangle from modified scarf (not the reverse triangle, although you can do that as well) by stepping over the arm with you near side leg straight into the triangle. You can get it also from normal 100 kilos side control, but I haven't had that much luck with that setup.
I haven't been able to get the triangle from back mount either, which is something I want to get better at.
Look for some Judo newaza vids to find some awesome ways to attack the turtle position with the reverse triangle.