I once set up a blog with the flat-file-cms grav.
Its free, fast and you dont have to deal with sql databasestuff.
I then implemented it into a 100%wide/height centerfixed iframe on the RM project.
This worked quite good but there for sure is some work to do on the gravsite to fit the blog onto the RM styling of your page. But its basic css work, allthough a bit confusing to dig through it and find the right values.