But if those foreigners were massively buying your domestic assets you wouldn't have a current account surplus.

It might be possible for Germany to create a 'Euro- Deutschmark' funding market, analogous to the London Euro-dollar funding market, but such a market might be prone to more volatility and gaming as it would be a much smaller market. And then BuBa would acquire the same obligation of lender of last resort wrt Euro-Deutschmarks as the Fed has towards Eurodollars and Germans could have a major hissy over that. And the gaming possibilities could make the 'mark' the subject of a double entendre joke amongst FX traders.  

"It is not necessary to have hope in order to persevere."