Londe is an obsolete word for land, in the sentence quoted it means the region of or tract of Rumbelowe. The name 'Rumbelow' is a surname in England; more than one district has the name- one near Birmingham, one in Aston, another a division of County Warwick, and one in Staffordshire known in 1430 as Romylowe- the exact locations are now unknown.
http://www.genuki.org.uk/big/eng/DBY/NamesPersonal/Rumbelow.html.

Genealogists have looked into the surname, and the above is from their researches.

The OED has no reference to rum in their article on Rumbelow.

I was giving the various meanings of 'rumbelow' as printed in the OED; none is specifically meant to relate to the song.

Rumbo (rumbowling) was a grog (mostly rum); no indications of a relationship to 'rumbelow.' Rumbo was a slang word for rope stolen from a Royal shipyard, and also slang for gaol (jail).
Rumbowling also was a slang term for anything inferior.
OED


The name as used for a type of carriage is a late one. No idea what type of carriage is meant; could have been the name of a maker, or a reference to the ride or sound as the vehicle moved along. The curator of a carriage museum probably could help.