Several years ago, I discovered a very different method on YouTube. Ended up ad libbing and adding expanding spray foam to the mix. I was so happy with the results, I made some "How To" videos and put them up on YouTube.
I'd recommend you go check this OGR thread from 2017/2018. It's only 2 pages long total and there's links to the "how to videos" which are still up on Youtube. I never make my rolling hills/mountain scenery any other way. But everyone has their own preferences.
Check it out: https://ogrforum.ogaugerr.com/...abric-batting?page=1
The photos are typical of the results you can expect to achieve.