I think stakes are a good way to go if they can drop loose if the kite pulls them out of the ground.
Crossed stakes are used by a lot of show kite people, often in pairs as shown below.
If the straps are set up properly they stakes will drop free of the strap if the kite pulls them out of the ground.
Here's an example with a strap with a loop in the end. Works well with large loop of webbing or heavy line also.
(graphic from Barry at WhataKite)
The crossed spikes do need to be oriented properly for the general wind direction but can handle the lateral forces in general and an arc of pull as the wind shifts better than solutions that are intended for more vertical or static force.