I think the idea of a "dirty" glider is a great idea, but will set one up for losing parts of the glider, like the flaps and ailerons, then the glider itself. Most gliders have airspeed limits on gear, flaps. I always had a very small level installed in the middle of the panel on my gliders (a level that can be installed on an AH). But then I have had much training with parcel panel IFR. Another poster mentioned ball (yaw string), airspeed, compass and altimeter can keep you in control, yes it can, but you had better have much practice and not have to scan from canopy to various parts of the panel to get all this information. Go rent a 172 and instructor, you will see how difficult it is, and a 172 will fly perfect without the pilot input.

I think a plan is the best, know the benign spiral characteristics of your glider in various configurations. Have a GPS coordinate for low ground, get some IFR training, get a vario with instant on AH, if you are below manuovering speed open the airbrakes. If you are not confident of your IFR skills try to freeze the controls instead of chasing instrument indications. Get a good flight instructor and practice your plan. Talk to other pilots about your plan and do not make any sudden control inputs unless you have a visual of the horizon. I saw someone posted that Bob got caught between two cloud layers. This has happened to me in both helicopters and airplanes, while you are not hard IFR you essentially are as there is no horizon. Same thing can happen in haze or low light.

No one mentioned spinning through the clouds. My personal view is that unless you know the sustained spin characteristics, you are likely to end up with the spin turning into a death spiral.

Good discussion though with lots of ideas to process.