Can I tap Baited Hook without friendly units on board to recycle 5 cards from my deck?

Ruling: No, you cannot activate Baited Hook without a friendly unit on board. To put an ability on the chain, you must have all valid targets available, and Baited Hook's activated ability requires targeting a friendly unit.

Sequence:

• When activating an ability, you must choose valid targets
• Check that all targets chosen are legal
• If targets are not legal, you revert the action and the ability does not enter the chain
• DAMAYC (Do As Much As You Can) only applies during resolution, not when putting abilities on the chain

Nuances:

• This differs from Harnessed Dragon because playing Harnessed Dragon does not have an ability - you play it first, then its triggered ability triggers and needs a target to enter the chain
• If you successfully target a unit with Baited Hook but the unit is removed (e.g., by Gust) before resolution, you still reveal and recycle the top 5 cards, but cannot play a unit since the might value is no longer available (mistarget/DAMAYC applies)
• The card uses targeting templating (rather than "you must" templating) specifically to allow interaction by removing the targeted unit in response