Quick and easy solution. Forget trying to remake the original contruction in plastic, instead use a strip of metal in a broad 'U' shape. Glue one upright inside the interior face of the front of the tender chassis with cyano or araldite. Depending on your curve radii you can either stick with the dimensions from your other V2 tender, or use this opportunity to close the cab to tender gap by having a shorter link. (By cutting off the projection from the cab floor and installing a shaped fall plate above, and also trimming back the moulded on intermediate buffers on the tender front, mine are coupled at scale distance, and will still go round 30" radius curves. Makes a worthwhile improvement in appearance.)