Henrietta has an auxiliary tank. Custom made and exact fit in the space we had. Took a lot of measuring and even a cardboard mockup to make sure it fitted. The professional that made it added a single (unwanted) item which meant it didn’t fit so that was quickly rectified in his workshop and the offending drain welded over. It would have been nice to have a drain from the splash bowl but i didn’t specify one. Its a proper job and at £200 was a good price. Double baffled even.
You may be wondering how it’s plumbed in….maybe not. It’s a gravity feed into the main tank breather. The drain is T’d into the breather as close to the main tank as possible and the auxiliary tanks breather is connected to the main tank breather a bit higher up. Gravity and levels does the rest. The flow rate from this tank to the main isn’t super fast but in 10 or so minutes the ~45 litres is down across into the main tank. We think it will hold nearer 49 litres with extremely careful filling.New range is now 670 Miles or 1080 Km @ our shakedown average of 25.5 MPG (UK Gallons). We will also carry 40 litres of backup in 2 standard underslung Jerry Cans.