Trouble is, that works better for some TLs than for others. At the risk of committing a mild heresy, successful Sealion isn't too bad in that respect, since an implausible military success doesn't make much difference to the political consequences of such an invasion, which would be about he same however it was accomplished.
OTOH, if we take the OPs voting figures seriously, the Democrats have not only missed out on the Presidency (unlikely enough in itself) but have in all probability been also wiped out in Congress 1920-style. Such a huge loss of votes would surely be too great for ticket-splitting to overcome Yet this is even harder to swallow given their huge success only two years before. So we have an implausible PoD leading on to even more implausible results. Sorry if I sound like a spoilsport, but for me this is a WSoD too far.