@mutineering @CP_ PDN It is possible to set up and reuse the LVM partitions.
I use LVM on most if not all set ups at work, those being mostly RHEL, but I did set LL4.x on my laptop with LVM's.
The major benefit (at least for us) is resizing the LVMs on the fly if there is available space in the VG (volume group).
I set up my laptop this way to see if any differences (not that I really see)...
Now, in the set up LL will set up LVM for you - I chose to configure mine different and set mine up prior to install.
I don't recall right off but I know sizing was part of it - maybe used it all I wanted to resize later... etc...
As for reusing, I don't see why not. at the minimum - choose Something Else during install select the Root LVM, you want to choose to format and set as root and install...
If for whatever reason this wouldn't work (formatting), while in the Live environment manually format/setup the Root LVM then the same Something Else choosing to install...