Cybex car seat - sorry not really pregnancy

[Fluffy05]

Hello

We have an Audi a1 and are trying to install the isofix base but it leaves the car seat too upright so baby would be leaning forward

The manual says to place a towel or wedge underneath the bottom of the base between the base and back of the seat in the car so that the isofix is propped up and the car seat is level and the indicator is flat

Is this safe?
Does anyone else do this?

I did exactly the same thing with cybex isofix base in the back of my polo.
As the manufacturer recommended it I was happy re. Safety although there may be conflicting views. Can't see why though as it doesn't interfere (that I can see) with how the base works.

Should say I used a pool noodle though - easier to wiggle about to find the optimum position! They cost about £1...