I would lean towards the mortise and tenon joint with a bolt higher up on the mortise where the tension forces are the highest.
I did a run of 17 cherry beds and used a similar joint. These are the bed bolts we used but I am sure you could make or find similar.
https://www.leevalley.com/en-ca/shop/hardware/bed-hardware/connectors/40445-bed-bolts?item=05G1701
We used the domino to cut mortises in both the rail and the post, then glued in the loose tenon into the rail. If you want the outside end of the treads to me floating, you will need a lot of strength in the joint to resist the pull forces. With the mortise and tenon both glued and bolted, I think it would be up to the task if your wood dimensions are correct. I think a longer mortise into the post than we used would be advisable. Our were 2".
I attached a picture of the bed rail end when it is ready for finish sanding. You can see the hole in the rail to insert the dowel nut. Depending on the design, you may need to plug those.
Good luck with it.
I did a run of 17 cherry beds and used a similar joint. These are the bed bolts we used but I am sure you could make or find similar.
https://www.leevalley.com/en-ca/shop/hardware/bed-hardware/connectors/40445-bed-bolts?item=05G1701
We used the domino to cut mortises in both the rail and the post, then glued in the loose tenon into the rail. If you want the outside end of the treads to me floating, you will need a lot of strength in the joint to resist the pull forces. With the mortise and tenon both glued and bolted, I think it would be up to the task if your wood dimensions are correct. I think a longer mortise into the post than we used would be advisable. Our were 2".
I attached a picture of the bed rail end when it is ready for finish sanding. You can see the hole in the rail to insert the dowel nut. Depending on the design, you may need to plug those.
Good luck with it.
