Can't send mixed data and text in AppleEvents ReplyString

Changes between Xojo R1 and R3 in the way AppleEvents deal with strings resulted in the inability to send structured data (raw bytes) and text to other apps. This was fixed when using StringParam("—") by allowing such data to be sent (as type data) if the string encoding is set to nil. I’m running into the same problem now, though, with AE.ReplyString. What worked in R1 fails in R3. I’ve filed a bug report

feedback://showreport?report_id=30601

and I’m hoping that the same fix, using the encoding, will be implemented here. But for now an important feature in my app isn’t working. So my question at the moment is, is there a workaround for this problem?