I finally found the tool I was looking for, it does exist. A sounddata.arc extractor for Dream Team that works.
Using the tool on the .arc file from the full game (yes it works on the full game) extracts 5 folders, 0 - WAVE, 1 - SE, 2 - SEB, 3 - STRSE, and 4 - STRBGM. The .rsd files in folders 0-2 can't be read by VGMStream, but 3 and 4 are readable and can be converted.