I think your ability to do this will just depend on how you are feeling which, unfortunately, can't be predicted beforehand.
I am 27 weeks pregnant with my first and have been surprised and somewhat disappointed at how much I've had to cut back my activities and work-outs in the past few months. I was in very good shape before getting pregnant (bike rides of 30+ miles, lots of hiking, yoga, running, etc.) and thought this would enable me to be fairly active during my pregnancy. My 1st trimester and the first half of my 2nd trimester were fine. However, beginning in the middle of my 2nd trimester I started having to cut back on my activity level WAY more than I thought I'd have to due to a number of factors. The biggest issue is that for the past few months I've been getting very uncomfortable Braxton-Hicks contractions every time I walk even at a moderate pace. I'm also a lot more winded than I thought I would be. So, I basically now stick to strolls around the neighborhood, yoga, and light swimming. I certainly couldn't do a backpacking trip right now (altough I'd love to! I miss hiking A LOT.)
My point is that I think you just don't know until you're there and it's different for everyone. You just have to wait and see. Good luck!