42 miles on a Gen2 is roughly 75% of the battery range, and a full charge on L1 takes ~11-12 hours at 12A. So, if you're actually able to charge at 12A (meaning there are no other loads on the same circuit) you may be able to recharge fully over an 8hr day. If, and this is more likely, you have to drop down to 8A, you won't get a full charge, but you'll probably get enough to get back home no problem.

The factory EVSE is totally fine in the rain, you don't need to search for another waterproof one or worry about covering it up. Just don't leave it sitting in a puddle. J1772 extensions are expensive, you're better off getting a 12- or 10-gauge extension cord and protecting the 120V plug from water using something like this.