What type of vehicle are you taking?
For me, if I think I'm going to be leaving my SUV unattended for any duration, I'll take the pricey stuff with me - there's just not enough hidey-holes in the thing to hide bigger gear.
I'm much more secure leaving my sedan unattended with gear in the trunk.
Now, my old VDub bug (1972 model) was about as secure as a garden shed - I was able to break in through the vent window in less than 15 seconds with a coat hanger, without doing any damage to the vehicle. Had that broken into a few times...even the stereo wasn't worth stealing from it, so I never had much loss - loose change, mainly.