On my last trip I checked and topped off the oil at my garage before I left and forget to replace the cap. I started smelling oil about 150 miles into the trip and pulled into a gas station to check it out. I realized I forget to replace the cap and left it on my work bench. Very little oil had even come out. I got a roll of tin foil, folded it over a few time covered the fill hole and used the rubber sound mat to hold it into place. I drove another 1500 miles before I got a replacement.
Don't over think it. You will not damage anything driving 50 miles.
1969 Ser IIA 300 Tdi hybrid
2002 Ford F250 Crew cab 7.3 diesel
2003 VW Jetta wagon 1.9 Tdi 5 speed
1995 Range Rover Classic 300 Tdi SoftDash (My Son's)
"Be the person your dog thinks you are"