+1. With ability for validation, drop down menu's etc.
If it helps, I have some hard coded pages that do this? With fallback validation for mobile devices too. It's a little messy but it works a treat.
1/ my_page.php in ROOT.
2/ my_page_submit.php in ROOT.
3/ my_page.html in template folder.
4/ A small core code change to viewforum.php in ROOT.
5/ Additional/optional change to overall_footer.html in template folder, to add fallback mobile validation. This adds jquery add on from a CDN.
When you view a chosen forum, hitting 'New topic' takes you to step 2 (my_page_submit.php), the form is filled in, and then posted. It actually goes to the edit post screen so people can edit/add pics etc. It's all probably a little oldskool regards an Extension though...