“Build your own website” - Developing a CMS with Vague Requirements on a Tight Deadline [closed]

Question

I'm a Java developer in charge of making a product which allows clients to "build their own site". I've spent a lot of time looking into Liferay, as I don't have any experience in building CMSs, and want to either use it, or get ideas of how to build a decent system.

The time line is short, requirements are vague, yada yada

Is Liferay a good technology to work with when showing the client (who may be very low on computer expertise) a user interface to build a site? The thing is, I want the power and flexibility to avoid the learning curve in building a CMS like product, but I don't want to waste time learning a new technology only to find its over-kill, or can't do the simple - but uncommon and unimplemented - things that we are asked to add as features

Ideally I'd like to provide multiple web interfaces to the core API to build the sites - one that is very powerful, and another that is watered down and easy to use.