You can declare a charge on anything you want to declare a charge on. If you decide not to declare a charge, then you can opt to take a Ld test to move as normal. If you fail that Ld test then you have to charge the closest enemy.
So, one way around the "probably going to fail Ld5" test is to always declare a charge against a suitable target if there are any targets within charge range. That way you don't have to bother with the Ld test, and you don't put the power of "what gets charged" in the hands of your enemy.
The other choice, as Stonecutter said, is to just look the other way. They can't charge what they can't see!
And one more choice, for turn 1, would be not to vanguard outside of your Generals Ld bubble. By turn 2 you should be setup for the charge you want to get off, so frenzy won't even be a problem by then (you could be 30" across the board by the beginning of your 2nd turn with an average 17" charge range ... you should be picking your target).