With the large mail in vote, an appointee before election day seems likely.
Yep. It's pretty much needed as if the election is contested and needs to be decided by the Supreme Court, not having a justice will be a disaster. Also presidency ends on January 20th - you can't go without a justice for 4 months.
Why can't we go without a justice for 4 months? After Scalia died we lacked a justice for nearly a year.
https://en.wikipedia.org/wiki/Merrick_Garland_Supreme_Court_...
Because this time, most likely there will be a contested election. And because this time it's different because both the WH and Senate are held by the same party unlike 2016. SC judge needs both Senate and WH and that was not the case in 2016.
I don't think it's possible to remove the election math, though. Whatever he does, it could influence voter turnout for both sides.
There's also the possibility that something about the election will be disputed and go to the Supreme Court (as happened with vote counting with Bush v. Gore in 2000). So Trump might decide he wants his appointee to already be serving before election day if he thinks that would be more in his favor.