It is possible, but not sure if desirable. You will loose automatic config for freepbx when installing on a different server.. you can overcome this issue by setting up fancy network configs (passwordless ssh access, executing autoconfig scripts on the asterisk box *From* the raspberry. Also, the raspberry startup time is like 2 o 3 minutes... once it runs it works fast, but startup times are super slow. If you want to try, just install fop2 on the raspberry, then setup the manager host to be your remote asterisk box in fop2.cfg, and finally copy the autoconfig-* script to your asterisk box /usr/local/fop2 directory, and modify your raspberry copies of those scripts so they execute the remote counterparts via ssh (with passwordless login), something like:

ssh remotehost /usr/local/fop2/autoconfig-users-freepbx.sh

Best regards,