Ok, so I took a shot at the double monkey fist. (Successive monkey fist? Fist in a fist? I'm not sure what to call this.) The cord is gutted 550 paracord, which is ~3mm in diameter. While I would never use this cord itself to hold anything of value, true 550 paracord could hold a robot. (The 550 comes from its static load rating, 550 lbs.) To make this knot, I put an Ashley Stopper at the end of the line, then tied a monkey fist around the Ashley Stopper. This first monkey fist had 3 wraps per side. Then, I tied a second monkey fist around the first one. The second monkey fist had 6 wraps per side.
I am pleasantly surprised with the result. I actually made a few small mistakes on the first monkey first, resulting in a less spherical knot than I would like. After tying the first monkey fist, I wasn't very pleased from how it was turning out. even aside from my errors, it wasn't looking good as a robust stopper knot. But after the second monkey fist, I felt much better about it. The amount of length taken up by this knot is astounding, but considering that the goal is a sphere at least 9 times the diameter of the rope making up the knot, it's not too surprising.
Tomorrow, I will try it again. I'll do a better job on the initial core (I might try a different knot for the initial core.), I'll make sure to rectify any errors on the first monkey fist, and I'll switch to only 5 wraps on the second monkey fist. Currently, it's quite loose around the corners and there's a bit of folding in the sides, which are both signs of there being one too many stands per side. Eventually I'd like to buy some real paracord and try out this knot on something that actually resembles the DAVIT, but until then, I can only recommend that teams consider this knot as a potential option and try it out themselves.