Water leak help

I have a 2011 Outdoors RV 18' Back Country travel trailer, and have had some mysterious water leakage that I'm having trouble finding. Seems to be under the hot water heater, with some migration beyond fore and aft to areas under the sink, etc. Sink connections and drains resealed. Doesn't seem to produce water under the cabninetry all the time, just occasionally. Seems to be noticed after we've towed somewhere. The water heater sits mid-chassis, right above the wheel wells, right under the stove. I've checked the wheel well sealing, seems OK. The hot water heater PEX connections were somewhat loose at one time, both are snug now and the water has appeared after a tow again. Water heater fittings are now tight, the brass nipple on the inlet is solid, as is the plastic check valve outlet....holds pressure without visual leaks...I've read that these plastic check valves can be problematic, but it appears to be fine. Styrofoam wrap on water tank makes further diagnosis difficult.

The water under the cabinetry under the water heater area is always clean, not dirty, which leads me to suspect something with the water heater. It's a Suburban 6 gallon model.

Windows, all sidewall sealing is maintained and doesn't appear to be a source for water intrusion.

Thanks for the words of advice!