The earlier versions on broadsides are Charlie related and a couple be seen on line.

http://ballads.bodleian.ox.ac.uk/static/images/sheets/10000/05300.gif

https://digital.nls.uk/broadsides/view/?id=14916

The Loch Lomond line is sometimes Ben Lomond the Loch not mentioned. I haven't seen the 1840 Dunn song book, but it is quoted in a 1902 newspaper.. and if it is the same- this is still Charlie related and not the general version we know. So the oft quoted fact of Lady Scott having supplied the 'modernised' lyrics would not be accurate.
Newcastle Journal 4th Feb 1902.
                              
BONNIE BANKS O’ LOCH LOMOND.” A Lady very kindly sends me 2 version of the above song which I have not seen before; nor many of my readers, mayhap. It is copied from a book of manuscript music about 50 years old. There is no chorus as in the modern version, and the piece bears this record: —“Words by a Lady: arranged by F. Dun.” As my correspondent observes, this version indicates the character of the ‘trouble’” referred to in the second. The song is, in this case, entitled “Bonnie Loch Loman’ and runs as follows:—

By yon bonnie banks and yon bonnie braes,
Where the sun shines sweet on Loch Loman,
Where we hae past sae mony happy days
On the bonnle, -bonnie banks o’ Loch Loman,

0, ye'll tak’ the high road
and I'll tak’ the low road,
And I'll be in Scotland before ye;
But trouble is there, and mony hearts are sair
On the bonnie, bonnie banks o’ Loch Loman.

‘We'll meet where we parted in yon shady glen
On the steep side o’ Ben Loman,
A When'in purple hue
the Hieland hills we view,
And the moon Iooks out frae the gloamin’.

Still fair is the scene, but.ah! how changed are-the hopes we fondly cherished; Like a watery gleam - like a morning dream
On Culloden Field they hae perished.
Ah! many that met and freely did rove,
Now ’mang the brakin are hidin’

An’ men guid and true are hunted frae view,
An’ exile or death are abidin’,
Wi’ his fair youthfu’ face and his native grace,
His plaidie in the breeze wavin’ lightiy,
His buckies shinin’ clear, his very sight did cheer. Oh! handsome were the looks of Prince Charlie!


The words we all know with the wee birdies sing etc. and tidied up into 'modern' form are published in 1876 Christies Traditional Ballad airs, and can be seen on-line.

www.scribd.com/document/492760873/Christie-W-Traditional-Ballad-Airs-1876-vol-1#

It is also published in the 'modern' form in the 1885 book Songs of the North Macleod and Bolton with arrangement by Malcom Lawson. This can be downloaded on-line.