Use forum plugin with different theme on same domain

I want to make a forum but have experienced that Upfront doesn't respond well to virtual pages.
Could a solution be to have different themes on the same domain?
I like the AnsPress features and they provide a theme as well.
Is it possible to run to themes and maybe clone the header made with Upfront to AnsPress theme so it is not to obvious that the site is using different themes?
Could you provide a simple step-by-step if above is an option?