'It's possible to believe that a "remain" vote is the best choice, while also believing that the EU is a flawed institution.'
It depends how important you think national sovereignty is. Corbyn believes in socailism and nationalisation and opposition to capitalist free market ideology in some instances and those may not all be allowed under EU corporate rule, just as Syriza found out in Greece where the unelected Troika told the socialist government what they were allowed to do.
'if you'd been shafted over the Scottish referendum, would you want to win Cameron's referendum for him?'
This is much bigger than Cameron, this is about democracy and sovereignty. Cameron will soon be out of office, but the EU decision will last for a very long time and will chain the UK govenment to the undemocratic EU.
'I honestly can see very little strategic benefit to Labour as a party in supporting either side.'
I don't think Corbyn thinks in strategic electoral terms because he is principled. I think they have forced him to go along but his heart is not in it and the people will probably see that.
'can you honestly imagine he would feel comfortable standing alongside unprincipled political chancers like Farage and Boris?'
I don't think that Corbyn sees politics as about personalities, for him and Tony Benn it is about ideas and principles. O some issues, Corbyn agrees with Farage despite their personality differences. But Corbyn is overpowered by the Establishment Labour faction who agree with Cameron about staying in the EU.