I have installed Invision Community 5 beta 5 on my test site. The plan is to upgrade this site after I test a bit more.
The beta site is at https://testing123.info
Stop by and abuse it. Guest posting is turned on. If you would like to play around in the admin send me a PM over there and I'll move you to the admin group.
I also have a site live on IPB 5 beta5 at https://forumseohelp.com
Thanks for your help.