Hi Gerberasai,
I just have one additional question:
What would you recommend in terms of a foundation? We are placing the mattress on a convertible crib (full size) and need the foundation to be very low since it’s for a toddler. Is it necessary to have a foundation or are slats by themselves sufficient? The one at spindle is almost 8in high and that will not work for us.
A flat support surface that has no flex and has either a solid surface (although I would consider adding some ventilation under it in this case … see post #10 here) or that has slats that are no more than 3" apart will be fine. There is more about the different types of foundations that are most suitable for different types of mattresses and some good options for each of them in the foundation post here.
I’m not sure what the specifics of the support system are in the convertible crib but if the support surface of your convertible isn’t suitable for using directly under the mattress without a foundation and you need a very low profile support system then a bunkie board or slat conversion kit would probably work well. There is more about choosing a bunkie board in post #4 here and there are some good options listed in post #4 here.
Phoenix