More Ux-friendly question navigation

I've always hated the way built-in navigation works in Storyline questions - the Submit button appears in the space usually reserved for a next button, and the next button (if you have one) is shunted to the left.

I get that this is because there's a 'continue' button in the feedback slide, but it strikes me as bad interface design to have different ways of advancing to the next slide. So I have been trying to come up with a solution so that users can use 'submit' to submit their answer, with the submit button then changing to the usual 'next' button so they can advance to the next slide. This means I can shift my feedback to a smaller space at the bottom of the screen, so it no longer obscures the question text. This also works when users revisit previously answered slides (if we don't want them to reattempt questions)

With me so far?

Anyway, here's what I did - I hope it's useful for other people who don't want to have different navigation methods on question slides.

Replacing Submit buttons:

Create a true/false variable for each question with default value of false (e.g. q1attempted == false)

For each question slide, include prev, next, and submit buttons by default
When revisiting, resume saved state.

On the base layer:
Change state of next button to hidden when timeline starts
Change the state of the next button to normal when the timeline starts if q1attempted is equal to True
Submit interaction when user clicks Submit button
Jump to next slide when user clicks next
Jump to prev slide when user click prev

On the feedback layers
Change the state of the next button to Normal when the timeline starts
Set q1attempted equal to True when the timeline starts
Change the state of the submit button to Hidden when the timeline starts