It has been more than a year since I've asked this question. So, here are the rule modifications that I've play-tested. It seems to balance well, though I would like the game to go a little longer.
Objective: Get 12 victory points before 3 years are up.
Remove the following cards from play: "Conflict" event, Merchant, Herb Woman, and all Attack cards.
It is the same pile.
As in the English rulebook (p22):
Examine your chosen stack. You may choose any one card from that stack. You may also choose not to exchange any cards. Place your discarded card at the bottom of the stack and return it to the table face-down.
Late reply is exceedingly late, but oh well. I tested these rules out and liked them; I also came up with some modifications I think add a little length and tension to the game.
Objective: Get 16 victory points before 4 years are up. (N.B. this is theoretically extensible for use with add-ons et cetera- the 4VP/1yr formula seems to balance decently.)