Auchenlaich sounds a lot like Long low in description, which imo doesn't fit with the Dorset Bank barrows using a comparative approach beyond the fact its a very long mound used for burying people.

On the subject of Bank Barrows, Formicant (or anyone else nearby) there is a very Dorset bank barrowesque mound pointing straight at Pen Hill long barrow on the edge of the Mendips. So if you are round that way at any point...