There's ZERO precedence for a Custom Union that is BETTER than being in the EU. There's no reason to think that the EU has ANY reason to encourage the break up of the EU - which would happen if the UK ended up better off - and no reason to be hopeful for magic solutions.
I don't think EVERY leave voter is a RW racist, but they ALL voted for a campaign that WAS racist.
Wether you have to be a racist to throw your lot in with racists... you tell me. Then again, I can tell you that the UK has 50K hate crimes a YEAR, after Brexit was confirmed hundreds of racist attacks happened, and even Corbyn thinks the UK needs to take back control of its border... you can explain that in non-racist terms if you'd like, but... all facts point to the UK economy being hurt by a shut border... so if it doesn't HELP the UK... I'm sure you'll have a way to twist that to be not xenophobic. but I'm also not sure I'll buy whatever it is you'll be selling.
Finally, thanks for your commiseration. You're absolutely right that being screwed by the UK is pretty much the norm for Ireland. At least this time we have the EU on our side.
If I were you, I'd get on that Swedish passport post haste. There's no reason to assume the EU and the UK will reach a deal, and if they don't you'll illegally be in the EU. Not that the EU is gonna come after you, but they could easily cut off your access to any benefits, bank accounts, etc.
Best of luck, and I hope it works out for you... if it does it won't be because of anyone in the UK though I'd wager.