So rather than code anything yourself, just give htem requirements that read like a to-do list for yourself, after you've already doen all the theoretical leg-work:
#1.1 to-do: when this form is submitted, pop up this confirmation form:
#1.1.1 Confirmation asking if user wants to leave page? #1.1.1.1 if user clicks yes, redirect them to the link clicked #1.1.1.2 if user clicks no, keep them on page.
#1.1.2 Form submission: when user submits form, run valdation
#1.1.2.1 if the name is not betwene 2 and 30 characters show an error "Name must be between 2 and 30 characters"
#1.1.2.2 if the email address is not in the format (one or more characters or numbers) @-sign (one or more characters or numbers) and contain at least one period after hte @-sign, then error message reads "Please input a valid email address."
and so on and so forth. stuff that makes your eye water regarding how incredibly, uselessly boring it is, like you're an executive and can't even tell your business manager to accept a bid, you must fucking dictate the letter itself.
However, as incredibly annoying as this process is, it takes you approximately half an hour to do a day's worth of work with it. You can review progress every day in half an hour over breakfast.
So, there is your answer regarding how to build a side project while you're working full-time: manage dirt-cheap disposible developers on Odesk or Elance who get off on adding absolutely zero benefit whatsoever of any kind to a project, besides doing exactly what they are told in painstaking detail.
This is being made from a throwaway because I haven't heard this idea expressed and people might not realize that this is the answer. As for my tone/style, I think it's completely wrong for any developer to agree to be in such a role, and the REAL correct solution would be to manage a creative, contributing developer who gets equity in the result and has more free time than you. But what do I know.