While I will (yet again) go back to my, "Loosen the belts, then, kiss your butt goodbye and hope for the best" statement, I will add....... know how to file a NASA report.

VFR into IMC (in the US for a non-IFR rated pilot) is a losing case.
Having some instruments and "lucking out" or, "bailing to save your butt" may work, I will hazard a guess and say, "Expect the FAA to want to talk with you...... at a minimum.......".

While it may have been done in the past (in the US) "legally", it's sorta hard to do (legally) in a sailplane today.

Best is to avoid the issue.
Yes, some instruments "may" save you/the sailplane
YES, you will talk to the FAA (especially is something gets broken..... very likely...).