Advice for simulating a bidding contest?

I've recently finished a game that involves players bidding cards in order to take actions. The rules are ready to go, and seem simple enough, but I've found my solo-playtesting less than great fun, mostly due to trying to "fake" a bidding war.

In the game, the players bid face-down cards, and reveal their bids when there are no more bids. The highest bid wins, and that player loses all the cards tehy bid, while the losers can't act, but only lose a single card they bod. So far, so good.

I've tried "playing" all the sides in a bidding contest, but I have to fake ignorance I don't have.

I've tried running all bids randomly, rolling a d6 and having each persona bid that total value, if they have it, and then play the resultant winner's action to their best advantace.

I've tried runing all players but on randomly, bidding one player's cards as best I can against a randomly detirmined auction, where the other players either bid a face-down card, or stop bidding at random.

I've also just tried to play the rest of the game, delcaring that each player discards 1-6 random cards, and the player discarding the highest value wins an action, while the others discard only one card and don't get to act. This skips the auction aspect altogether, but allows me to test the play of the rest of the game.

What a pain! All of these systems take a fast bidding mechanism and makes it a solo nightmare.

Any other suggestions?