Dave Shoup
Banned
Historically exactly those 'benefits' were on offer and ended up doing nothing to budge neutrality. Neither did the stick which both the British and American governments used often enough. The thing you have to understand is that the War of Independence ended in 1921. That is not even two full decades before the start of the Second World War. It had also ended in partition, an issue the Americans never even tried to engage with and the British had an understandably complicated relationship with. There is also the blunt fact that many saw neutrality as in itself a necessary act of independence rather than being an appendage of the UK.
Fair enough .... hence the suggestion in the OP that any such decision would have to come after the tide had turned. 1943 seems the most reasonable, given whatever POD it takes to move Irish government opinion. Obviously, it is all speculative, but I agree, it certainly would not have happened in 1939-42. Maybe in 1943 or afterwards?
Trying to avoid the easy out of "specific individual slips walking down the stairs" and miraculously policy changes, obviously. Was there nothing that would have persuaded De Valera? Other than a German invasion? The Irish Merchant Marine lost a fair number of ships to Axis attack, and that was - with the promise of L-L - enough for Brazil, Mexico, and Cuba, for example...