The last one apparently is a spar buoy, but shaped for low water resistance. This might be worth looking into. If you add a couple of plates outside of a cylinder you get a teardrop shape wich should give you a lot less drag and consequently cheaper transport and station keeping.
That “Orbiter” is a fine design,…something to consider in terms of “spar” based structure design.
I like the “wing” profile which allows for good mobility, less resistance then a cylinder when cutting thru waves. The submerge “bulb” (or ballast) I would redesign as a hydrofoil shape and give it a bit of “rake” of 10-15 degrees (adjistable) from the horizontal plan, aft, so it can develop “lift” under power. And power it aft of the bulb, thus applying force exactlly (or close enough) to the center of gravity.Thus, under power the whole structure will ride with very little degree of heel.
What is also remarkable is that the whole structure could be sailable. (save a lot on moving costs). The above the water structure can be rigged as a mast an fitted w/a main and jib (it looks like it has spreaders already,…). I will try to draw something based on what I said and post it.
Two Stars and Stripes cats were built, one with a conventional soft sail (Stars and Stripes S1), and the second with a hard sail (Stars and Stripes H3) built by Scaled. The hard sail proved faster, but the soft sail version was used in the defense because it was considered more than fast enough and had less chance of rigging failure.