As you probably know, DayStar made an SE/30 PowerCache that replaced the original socketed CPU and was contoured to very nicely accommodate the various features of the logic board. If your board wasn't socketed, you'd send it in and they'd make it so. Of course, most SE/30 logic boards aren't socketed and so any newly designed socketed adapter would only be compatible with a limited number of the remaining boards.
Similarly, the manual for Manabu's (artmix.com) PDS adapter specifies that it cannot accommodate a Turbo 040 and Micron Xceed card simultaneously. There must be something that kept him from making the two work together. One could, however, use a less capable 030 accelerator with that video card, though obviously the Turbo 040's performance is preferable.
While an internal SE/30 multifunction card that combines CPU and SCSI acceleration, high resolution (minimum 1024x768) and high refresh rate (minumum 85 Hz, with 120 Hz ideal) accelerated external video support with Photoshop acceleration, and 10/100 Ethernet would be the ultimate upgrade from my perspective, it would be great if I could at least use individual internal CPU accelerator, video, and Ethernet cards simultaneously. If one wishes to have all three enhancements with Manabu's adapter, s/he must settle for external SCSI Ethernet. If there was a way to expand one of the slots on that adapter to permit an internal Ethernet board, this problem would be solved, though space constraints become an issue.
After considering the limitations of existing adapters, some variant of this expansion chassis idea seems to be an alternative or even preferable solution. One concern here though is that those that were produced apparently could not accommodate accelerators, as the following excerpts from the July 21, 1992 e-mail "2-Slot Upgrade Options for the SE/30" (previously the result of a Google search) indicate:
"The Aztech 'Galexa SE/30' is comes in form of a kit that lets you (or Aztech, of course) build a modular Mac using your existing SE/30 motherboard, floppy drive, and hard disk. The kit includes a new case with room for 2 HDs, 65 watt power supply, FDHD drive, and two PDS slots. Because the original case and internal monitor are unused, this option requires that one of the PDS slots be used for a video card. The resulting modular Mac looks much like a IIcx or IIci. The Aztech option is probably of greatest interest for SE/30 users who need an extra PDS slot, but don't need an accelerator card -- color monitor plus ethernet, for example."
Note that this was a replacement rather than an expansion chassis--a sin that is likely out of the question for many of us.
"The Second Wave Expanse NB4 (or NB8) have 3 hardware components: an external box (25 x 55 x 10 cm) with 50 W power supply, PDS interface card, and special (read expensive) interface cable. One of the 4 (or eight) added 10 MHz NuBUS slots can be used for NuBUS video (for example, a MaxAppleZoom-compatible Toby frame buffer). The others can be used for any number of NuBUS cards, with the unfortunate exception of the only currently available NuBUS accelerator card, the Radius Rocket (all versions). The Second Wave option is probably of greatest interest to two kinds of Mac users: first, institutional users whose budget policies make upgrades easier to obtain and/or justify than selling an old computer to buy a new model, and second, users who need specialized boards for data aquisition and control (or extra serial ports) that are much easier to find (and pay for) in NuBUS form."
Other than producing a multifunction card, if possible, producing a NuBus expansion chassis that supports an accelerator (or which allows one to be installed in the SE/30 along with the chassis interface) and a bring-your-own ATX PSU would be the ultimate upgrade, allowing the use of more plentiful, varied, and affordable NuBus cards. Imagine an SE/30 that was equipped with a Turbo 040, Radius Thunder or comparable video card, PhotoEngine, Asante MacCon Ethernet, FWB JackHammer with a RAID array of 15,000 RPM drives (I prefer mirroring), etc. Some might suggest simply acquiring a Quadra, but having the SE/30's second, smaller monitor alongside a larger one provides great utility and in my opinion the SE/30 is the most visually appealing of any beige or platinum-colored Mac as well as the best expression of the Snow White design language. Besides, my understanding is that the large Quadra towers sound like wind tunnels, and a tower expansion chassis could be placed under a desk provided that the interface cable length was not a constraint. Something to think about, though the amount of work involved makes a multifinction card sound at least as probable (and thus equally improbable).