Personally, I found that by that point (8 months of breastfeeding) I could not boost my milk supply no matter what I did. I'm sure you'll get lots of advice for various methods, and by all means try whatever you can, within reason, but don't stress too much if you just can't get your body to do it. You've been at this a while now, and your breasts have settled into a pattern of supply/demand that can be hard to budge.
Your son must be eating solids by now, right? Might you consider just having him take formula for his liquid feedings and increase the solids a bit while you're gone? You can continue pumping while you are away to keep up your supply, and a few days of formula won't be the end of the world for him. And it sounds like he's already used to having a bottle and switching back to the breast, so that aspect of it shouldn't be a problem.
Anyway, that's my idea for you - most importantly, have a great time and RELAX while away with your hubby, that's such a great thing to do, and a luxury when your baby is still little!