Jessica Simpson -- Cover-Up Mission in Hawaii

Jessica Simpson and Eric Johnson are going to extremes to hide something -- like every inch of their bodies during their family vaca in Hawaii.

We've already seen Jessica covering up on the beach since announcing her pregnancy ... but during a Christmas Eve stroll on the beach even Eric was cloaked from head-to-toe while carrying baby Maxwell.

Far as we know ... Eric doesn't have a deal to drop lbs on Weight Watchers.

The only Simpson not in undercover mode these days is Ashlee Simpson ... who proudly showed off her bikini bum.