I looked on Thomas Hale's site. He doesn't have info about that med, but he did respond to questions about a couple of other rectal creams, including some steroidal ones. He says steroids don't pass into milk well, and he said a similar med shouldn't be any problem.
How about fenugreek? When I was nursing my 1st child, I worked outside the home for 3 days each week. I noticed that I pumped less Wed than I did Tues and less Thurs than Wed. So, I began taking fenugreek, and that seemed to help things stabilize.
Your milk production should respond to demand. Can you take a "babymoon," with baby in bed for a day? Or add a pumping session or two to your weekends? (Right after the morning feed seems to be a good time for me to get some.)
I agree w/the comment about co-sleeping, too. That can help, if you can do it.
When are your business trips? Will your child be starting solids by then? If so, maybe your stash will be enough.
Best wishes to you and baby!