You can use all 3, or just the two on the right also work great.
There are clip-on versions which don't require disassembling the bed, and also regular through-hole versions.
The design is parametric, so you can adjust parameters like hole size, clip opening, etc. Just go to this link and then change the parameters on the top-left. After that, right-click and export.

Note: If the clip-on version is too tight to put on, set clip_opening_angle to a slightly higher value. To generate the regular hole version, set it to zero.
The author marked this model as their own original creation.