I've been working with a machine shop/welder not too far from where I live on this. So far, I've had gas post base fittings welded into 11 sanke kegs. I've been using the slightly modified fermenter kit (installed a liquid post, poppet and dip tube on the fitting for the racking cane) to extract the finished beer, or mead when it needs to be racked. I was actually at the welder tonight getting four of those 11 kegs fittings welded. I have him working on making me some different TC caps to do more of what I want them to do. Since I don't have a welder, nor access to one, this is the best option for me, for now.
Once the new fittings are done, I'll have the best of both worlds. The thermowell to get the fermenting temperature, plus the liquid post and dip tube assembly properly fitted (not forced as it is now). They're going to drill/ream out the base fittings for the corny posts to accept the dip tubes for me. This will allow me to use them for both fermenting AND transferring. I'll be able to remove the post and poppet from the base, and slip a short piece of 1/2" silicone tubing on it, to connect an airlock (as you would with the kit from Derrin). Then, once fermentation is over, I'll be able to remove that tube, give it a short blast of CO2, to purge any stray air from the keg, install the liquid dip tube and corny post, and then transfer into either a serving keg, or another sanke keg (aging vessel, etc.) via another kit with a liquid dip tube in it.
I used a modified version of Derrin's hardware to do this over the weekend with two batches of mead that needed to be racked. When I get the new assemblies back from the machine shop, that will be even easier for me.
Now I'll need to decide what to do with the orange caps I have on hand, as well as all the bungs I've picked up to use. Especially, since I'm about to not need either of those items for most of the things I ferment. I'll keep the items for the glass carboys, for when I use them. I doubt I'll keep the ones for the BB, except [perhaps] one each so that I can transport water if/when needed.
Also, for those two batches that I racked this past weekend... I simply sealed the opening in the kegs with TC caps and clamps and put QD's on the gas posts that have bleeder valves and pressure gauges on them. I can see, at a glance, if ANY pressure is building inside the keg. So far, no pressure is building. Since they've been done fermenting for over a month, I'm not surprised at all. I also was able to purge the kegs of oxygen simply by using CO2 and then either pressing on the poppet in the post, or using the bleeder from the QD assembly.
