Freebsd root on zfs install

[Rance Hall]

I have a freebsd 11.1 server setup using root on zfs using a pair of
matching usb keys.

I have a pair of matching 1TB drives for data, and a pair of 6TB drives for
media.

I'm trying to minimize the number of disk writes to the usb keys so I'm
working on a plan to remount some of the zroot mounts onto the spinning
disks.

I've already moved /tmp and /usr/home

I'd like some suggestions of what to do next.

Here's my current output of "zfs list | grep zroot":

zroot                                            1.88G  10.2G    88K  /zroot
zroot/ROOT                                       1.26G  10.2G    88K  none
zroot/ROOT/default                               1.26G  10.2G  1.26G  /
zroot/usr                                         633M  10.2G    88K  /usr
zroot/usr/ports                                    88K  10.2G    88K
/usr/ports
zroot/usr/src                                     633M  10.2G   633M
/usr/src
zroot/var                                         860K  10.2G    88K  /var
zroot/var/audit                                    88K  10.2G    88K
/var/audit
zroot/var/crash                                    88K  10.2G    88K
/var/crash
zroot/var/log                                     400K  10.2G   400K
/var/log
zroot/var/mail                                     88K  10.2G    88K
/var/mail
zroot/var/tmp                                     108K  10.2G   108K
/var/tmp

I have my eye on /var/log and /var/tmp and adding a mount for /usr/local/


Thanks for your time guys.