No one told me I did not need a wood backing. My idea alone. Heck, you can use cardboard and not wood. I've seen that done. I should be able to use an old canvas print. I will just figure out a way to do the tufting or switch to wallpapering it instead. Nothing to loose if it doesn't work. I will Just re-do it.

Tufting is for a very experienced upholsterer. I'd rather have an untufted headboard anyway - tufting is a HUGE dust catcher.

Ohh no, tufting is not the least bit difficult. I have done it several times but always on somethings with a solid backboard. I found it fun the first time I did it. But I do agree that solid is far less dusty to deal with and I do love to clean. You have me turning my gears again.

Even if you can tuft with a cardboard or canvas back, it will not be very durable, and I'm afraid it might tear or otherwise get damaged. Instead of tufting, you could use an interesting fabric. I used African mudcloth for my brother's headboard:

I think cardboard will work. Anglo, tufting something serious like a couch might be difficult, but a headboard is pretty easy. This sounds like a fun DIY and, like you say, if it doesn't work, there's not too much lost. Are you planning on putting something behind on the cardboard side when you tuft, like another button instead of just tying it off?