Wow, a lot of off the wall ideas for a simple problem :h .
The REAL way is to use a ROLLER "CATCH" (the item you are looking for is called a catch, not a latch).
YOU CAN FIND HEREGuaranteed to NEVER, EVER fly open again...
Be prepared, they might be small but they pack a huge holding power punch (make sure your face is not close to your arm when opening :S )!
That type of catch was used in my Dad's 1960's truck camper and we never had a door open ever.
Solved all my door latch problems.. I used them in both of my TT rebuilds with success.
Cheap also at under $1 each! :B