Just to clarify a bit for you here mate, It may feel like you are being dumped on pretty hard... But the point most of us are trying to get across is that this just is not safe in any way. As for the guys commenting that your current setup is probably over limits as well, we would need more information to help you determine that but the payload of these minivans is deceivingly high.
At the end of the day if you don't ask the question you wont get an answer, and i do hope that you are not discouraged from future questions and perhaps helping others as well (sounds like you have a fair bit of experience as well)
I can agree with this statement. I can add that I do work at a dealer and see transmissions in these things burned up from towing things lighter. We also do handicap conversions on them and HAVE to re-engineer the suspension for them to handle the weight.