I might be misconstruing what you are trying to do but floating assignments are limited to instant clones (non-persistent). What is possible is dedicated, persistent VMs in which you create a automated full clone pool. You create an AD group that is entitled to the pool and as each person logs in they get automatically assigned and entitled to the next full clone(persistent) that is available in the pool.

When you build these style of pools at the end you simply pick a customization script (like when creating traditional full clones) that has commands like joining the domain etc.

What you want to select when creating such a pool is:

• At the 2nd screen (vCenter Server) select Full Virtual Machines.
• At the 3rd screen (User Assignment) select Dedicated and check the box for Enable Automatic Assignment
• At the 11th screen (Guest Customization) you will need to select one of your pre-built customization scripts.

This will then build a pool (you can manage how many VMs max, how many spare (for when 5-10 first sign in to get their new VMs). One each person signs in they will be automatically be assigned to that next VM in order.