Help with LVM & increasing metadata size

Hello,

We have a RHEL7 box with a large RAID (few hundred TB) allocated as a single volume group (data-vg) containing a thin pool (data-thin). Within that are 3-4 thinly provisioned logical volumes and 15 odd snapshots.

We are using 58% data but worryingly 73% metadata. The system was left to determine metadata LV size itself on creation of the vg, and we now notice it only allocated 128MB.

I am unable to increase the metadata size, because the volume group and thin pool use all the extents available and I read shrinking thin pools is not supported. (I do see someone has written a tool hosted on GitHub, https://github.com/nkshirsagar/thinpool_shrink but not sure I want to trust our data to it).

The host does have separate RAID1 SSD's for the OS. (It uses LVM for root/swap). I was hoping I could use some space on there to extend the data-vg, but it looks like I can't have multiple vg's on a single physical volume.

Is there any way out of this pickle?

Thanks!