I had a look at the Joey lift and all the images show it applied to a much larger (higher) rear opening than the Octavia wagon and even then it looks fairly tight.

The problem is that the Octavia wagon has a sloping sportback style that sacrifices some internal capacity and while there is reasonable height from floor to ceiling inside the boot area there is a fair entrance lip to negotiate and then a drop of near 100mm to the boot floor

I think the caddy is probably the better option for your requirements.