Given vote counting occurs at the county level, barring rare exceptions mail in-county takes at most 2 days to get to the election officials office, except maybe for some large urban areas.
Two weeks is ridiculous.
I wish. Sending mail across town (actually, less than 300 ft. from the post office):
Mail goes in big blue box, gets picked up at 3 PM. Mail travels 250 miles to sorting center. Mail gets sorted (someday, if there have been no days when the staff could not get to work). Mail comes back 250 miles (plus 300 ft.) and is delivered. I have seen normal lag times of about a week, and as long as six weeks. I got last month's insurance bill three days after it was due (I had just gone down to the local office and paid there).
So, no, at least in some places, you cannot count on the mail, nor even the postmark date, because it is postmarked at the sorting center on the way out the door.
One day, paper ballot, voter ID, in person or absentee (limited) but on you to deliver the absentee ballot by the close of polls on election day. And deploy ICE agents near the polls, just for fun.