I'm serious. There is fundamentally wrong with a company that doesn't even talk to an engineeer before selling a contract committing itself to developing a kind of software it has never done before within 5 days. I don't care how simple the project winds up being, sales people should not make that judgement call.

Given the time constraints and your lack of relevant experience, I can understand the choice to roll your own. After all rolling your own is a project of predictable length and complexity. Evaluating mature systems is not. With a 5 day time limit, you can't risk the possibility of deciding on a course after day 1, then finding out on day 3 that the existing tool forces you to do something differently than you were planning on, and you need to redo a day and a half of work.

However the result is that your product will be crappy and inflexible. You'll make a bunch of mistakes that existing templating systems figured out are mistakes. Plus it will be impossible to find anyone else with expertise in what you did.

If this is standard for your employer, then you'll have a lot of poorly designed crap to deal with. After a while everything that you do will be pain and frustration. Better to burn out early, before you're really pissed off, and take a new job than to stick it out in an environment that is guaranteed to make you unhappy.