We had the same issue. The problem is that the vinyl flooring is designed for home use where temperatures may fluctuate 5-10ēC, not a trailer where the temperatures can vary by 50ēC or more. My understanding is that the floor is laid down without glue and that everything - walls, cabinetry, fixtures - is installed and screwed through. Such an installation would be done in a factory at room temperature... but when it drops to minus 40 and the floor shrinks, it splits.
Here's ours - from under the bed and under the wall (to under the cabinets on the other side).
We were faced with a decision. We talked to the dealer - the floor could be replaced for $8/sqft plus $1500 for labour - a total of $2460 before tax (although they would glue it down this time). We ended up replacing it ourselves with TrafficMaster Allure flooring from Home Depot. Our cost? $650. The result?
We sold this trailer last week and the replacement flooring was still in top condition. We visited once or twice over the two winters since the installation and noticed that the tiles had shrunk, leaving gaps between. But when the weather warmed, the tiles expanded and the gaps closed.
The project is fully documented on our website in six phases. Check it out at Repairs - Vinyl Flooring Replacement