Funnel for next 6 months rolling

Funnel for next 6 months rolling

Hi

Is there a way to set the date field in Analytics such that you can see  a funnel for the next 6 months? 

Currently I can do a Custom date but that's a fixed start and fixed end, so I can set it to 6 months hence, but in a month that'll be the wrong end date. 

I can do Next Quarter, but that's too short a period, and misses out some of the current quarter before the next one starts. 

What would be great would be if there was a Next option, which then allowed me to choose days, weeks, months. Oddly I have a Last feature (from another post) so perhaps someone could enable Next for me?

Olly