Hi Andrew, it's not hard to figure. Measure length by the width overall for the square footage. Be sure to add about 5-10% for miss cuts and possible repairs. Not sure how much comes in a box or case but way to much is never a bad thing. It would be a bummer if you needed to fix something later and it's been long discontinued. I did the same thing way back in a class A and had a bunch left over. Over the years I used the wood strips for a bunch of small projects. Just the old 2 cents worth from a long ago flooring installer.
When doing a small flooring project like an FGRV you will usually need to allow more than 5-10% extra material to your requirements because there are a greater % of cuts vs the size of the job than in a typical 10x12 room. I use 50% extra as a figure and seldom have more than a few pieces left over. As Dave mentioned, you will also want to save the spares for future repairs.
BTW: Water plays havoc with most laminate flooring. As little as a spilled glass of water can ruin a complete RV floor if allowed to sit overnight. Be sure to get the kind rated for wet installation areas.