Multiple form options - CRM 2013

Hi there

I have 5 different application forms which I need to create on 5 different forms due to the size (tried putting them on one form, however there are too many fields for one form). What I would like is to have a + button on the "opportunity" screen and that to then give the option to select one of the 5 forms. Depending on the option selected it then shows the relevant form. What is the best way to do this?

Thanks