How do you install one comfortably FF on the plane?

We've always just used it rear facing and it's been fine, but on a recent ANA flight they insisted the cabin crew had to install it and when we boarded the plane we noticed they had put it FF and the buckle was right in the middle of my son's back and there was no way to make it comfortable (not with towels, etc). They wouldn't let us reinstall it rear facing so we ended up just having them gate check it.

I guess that is their policy but am wondering if there's another way we can make it work?

(Same flight they insisted my 2.5yr old had to be held on our laps during take off and landing. Is that right? I thought that was only for lap infants?)