Ansible2.3.1 Python2.7 with BigIP 11.5.1

I manage a large inventory BigIP's on TMOS 11.5.1. I'm trying to adopt ansible as an automation platform. My first task is to write a script that generates strong unique passwords for system accounts, root/admin and automatically update them on each F5 and store them in a cryptlocker. Ansible user and vault seem like obvious choices. They use ssh keys for auth and update the sha512 hash instead of the password. I also thought there would be better backward compat with my older versions of F5 software. I know there is no python ansible support before v11.6 because there is no REST API, so I am trying to use mainstream ansible modules.

I found that the v11.5.1 has Python 2.4.3 which will not work with ansible 3.2, so I installed ansible 2.3.1 in a virtualenv, where I have more errors, and the missing stdlib json or simplejson modules are on the F5.

My question: Is there a way to get plain Ansible to work on older F5's because of the python module dependencies?

ansible-2.3.1.0) [brian@fedora25 python-venv]$ ansible f511 -m ping
f511.chostner.net | FAILED! => {
    "changed": false, 
    "failed": true, 
    "msg": "Error: ansible requires the stdlib json or simplejson module, neither was found!"
}
(ansible-2.3.1.0) [brian@fedora25 python-venv]$ ansible --version
ansible 2.3.1.0
  config file = /etc/ansible/ansible.cfg
  configured module search path = Default w/o overrides
  python version = 2.7.13 (default, May 10 2017, 20:04:28) [GCC 6.3.1 20161221 (Red Hat 6.3.1-1)]
(ansible-2.3.1.0) [brian@fedora25 python-venv]$