Here are some suggestions I found in literature.
1) 10.1002/adfm.201700986
Your starting material was used in suzuki reaction in this literature.
THF was used as the solvent. The yield was 77%.
It looks like your SM should have good solubility in THF.
2) Karischin; Fedorenko - Ukrainskii Khimicheskii Zhurnal (Russian Edition), 1955, vol. 21, p. 373,375, Chem.Abstr., 1955, p. 14722
In this Russian paper, your SM was reacted with various diamines. This kind of condensation reaction was done in acetic acid. Maybe you can also try that.
I also find many reaction using acetic acid as the solvent. It looks like a promising solvent to me.
3) Solvent-Free Condensation Reactions To Synthesize Five-Membered Heterocycles Containing the Sulfamide Fragment (link: https://www.thieme-connect.de/DOI/DOI?10.1055/s-0035-1561371)I see many reactions between diketones and sulfamide to synthesis thiadiazoledioxide. It should be a promising route even SO2 group is electron withdrawing.
I highly recommend this literature (link above). You may repeat the procedure and use the acid mentioned in this literature.
Good Luck.