Other than Henry Wallace being seen as a liability in 1944, I think any other choice than Truman would’ve had little impact in changing the outcome. Since Douglas never ran a political campaign, it’s hard to determine how he would’ve approached it. Personally, he was a cad and dumped his first wife while he was on the court (and openly pursuing another). The media, of course, protected these elites from the public, so that might not have come to light. Whether he would’ve survived 1948 is up in the air, given how well he’d have related to the public.
FDR wouldn't have been vulnerable to such a tactic because he spent the entire election season insisting he was vehemently against the U.S. taking sides in the war, and the voters bought the argument (he even went so far to tell one woman "Madame, I have seen war and I hate war, and I can promise you that as long I remain President of the United States, your boys will never fight on foreign soil.")
Of course, Pearl Harbor immediately changed all that.
Had FDR's involvement with World War II been more akin to Bush's "War on Terror" strategy c. 2002 (which was the SLOWEST "rush to war" I've ever seen), THEN Lindbergh could have made the 1940 election a referendum on war.
A much more interesting "alternate history" scenario for me is Charles Evans Hughes defeating Wilson in 1916... and since Woody BARELY won re-election in real life, its much easier to come up with a plausible "Wilson loses in 1916" scenario than an "FDR loses in 1940" scenario.
Basically, all Hughes had to do was win a handful of more votes in California, and not do so lousy in the rocky mountain states.