Park used to make a very light thin pedal (15mm)/1" threaded headset (32 mm) double end wrench called the RW-1 that is light and small enough to take along. I don't see it listed on Park's web site but you may find one NOS at a bike shop.

I bought one to use with my S&S coupled travel bike as I had to remove the pedals to pack it.

Also, many pedals have 6 mm or 8 mm hex recesses at the crank end of the spindle and those can be used in place of a pedal wrench.