You said "I usually wire these into the pot as they can be top-heavy"
Have you got a pic of one you have done this on.
Here's a few shots that illustrate how I have done this. First is a pot that has a 'U' shaped wire extending through a pair of drainage holes.
And here is an example of it in use. A loop of wire is formed around the trunk of the tree and the vertical legs are extended through the loop on either side of the trunk. The vertical legs are then trimmed to an appropriate length and bent over the loop to secure the tree in place.
After this is accomplished additional soil is worked around the roots while applying gentle upward pressure on the plant. This results in a stable arrangement. Usually this is below the soil surface but I removed a little to show you.
Other methods of securing plants temporarily
can be used until the plant settles in and begins to stabilize.
These are Bamboo skewers sold in grocery stores for shish kebob. This may not be appropriate depending upon the type of pot you are using. Be creative and I'm sure you'll figure something out.