I only have 4 panels, so I only ordered two pair of MC4 Ebay connectors.
That's just enough for me to go series or 2&2 parallel for 1/2 the voltage.
I soldered them on. Found one 'body' had a problem holding the pin,
and the Ebayer sent me a new piece, which worked fine.
These connectors don't look so heavy-duty to my eye.
My guess is waterproof trailer hitch lighting connectors might work.
I guess they don't have to be that beefy,
if you always turn off the load
BEFORE making connections or disconnections.
You never want to arc these things. They might just weld in place.
I really like the way Anderson Power Pole connectors work and would
likely use them if I needed to add more panels. (That weren't in series).
For a
real temporary setup, I wonder if plain old electrical twist caps would work?
To prevent rain getting in,?, maybe rain-loops in the wires and place
the connectors up inside a plastic cup. Maybe even push some of that
HomeDepot electricians putty up inside the cup. To keep out flying snow..