For extended use:
Turn inside out - should give you at least 1, maybe even 2 more days on the road.
Yes, the t-shirts are pre-shrunk, but it still may shrink more depending on the heat of your dryer, or the number of six packs consumed. Use caution with either of these. Best washed inside out for first couple washings and hang dry, or turn inside out, put it back on, run through the sprinkler with a bar of soap and lay on the driveway till dry - whichever method fits your domestic skill level.
Hoodies and work shirts may shrink a bit - so save some of that electricity and hang to dry on the exercise machine like everyone else. Leave a little room to account for that beer and burger and you will be fine.
Enjoy your new rags