Depending on the client, I usually use either:

- A customized Django admin interface (https://docs.djangoproject.com/en/1.7/ref/contrib/admin/). Yes it's not ideal but it's often good enough.

- A fully custom admin UI built from scratch (Python/Django).

I don't know why you don't think Rails/Django is an option when developing "full-fledged systems".

For hosting, deploying with Ansible to a Digital Ocean VM has worked very well. A $5/mo droplet is more than enough for light - moderate traffic.