Change in training plan?

So I've been training for this awesome sounding triathlon: The XTERRA REAL Mountain Bike Triathlon with Super Sprint MTB Triathlon. However, the realization has slowly been dawning on me that, while I am pretty much on track with my non-swimming training, this triathlon's bike portion is a mountain bike leg. I haven't been on my mountain bike since October.

While I'm sure I'll ride down in Santa Barbara a couple of times before then, I am not confident about doing a 16 mile mountain bike ride pretty much cold.

I'm considering a few options.

1. Downgrade to the super sprint, for which the bike length is a more manageable 6 miles.

2. Switch up my training and do a half marathon at the end of April/beginning of May (maybe this one?) and do a later triathlon (like this one or this one or this one which one of my friends is interested in).

3. Suck it up and do it anyway.

I'm just not sure. Any advice?