One mans opinion: There will be NO harm with leaving as is and not attempt to fix this until you are on another project that gives you better access. As @micruz60 pointed out these bolts on the side cover are very low torque. Keep the others tight & you will be fine.
As @OGBeno says. Not a big deal.
Or take one of the correct bolts and match it at Ace Hardware or Napa. You will have one bolt head of a different size. BFD, how many times does one remove the oil pan not in your driveway with easy access to wrenches?