Hi Arik,  you are into the period covered by Church records and PRONI. My normal starting point is Ros Davies Co Down website, recently another record has gone online the Tithes   
Apart from surviving census, the main substitute is Griffiths valuation about 1860, then on a much more limited scale the next earlier substitute is The Tithes Applotment records which in Donaghadee were taken in 1834.
Neither exact spelling of those names is to be found there, but there is a 
Huston, Robt. Townland: Ballyraer Year: 1834 
http://www.irishgenealogyhub.com/down/tithe-applotment-books/donaghadee-parish.php#.VTCo0UuDoYUNow back to Ros Davies website which you may know all about, nevertheless in case you don’t and I defineitely don’t know what she is offering here goes 
http://freepages.genealogy.rootsweb.ancestry.com/~rosdaviesMap section of the townlands of Donaghadee led me to see the nearest spelling is Ballyrawer, which in turn led me to her Placenames database, which gives 
Ballyraer   Donaghadee   .   alternate spelling for Ballyrawer townland in 1659 census    PNNI V2 p 186
Ballyrare   Donaghadee    .    alternate spelling for Ballyrawer townland in 1833 
V17 p 124 OSM; PNNI V2 p 186
So next I looked to see If Robert or his descenfants still lived there in Griffiths time see 
http://www.askaboutireland.ie/griffith-valuation/There is lady Mary I Blakiston Houston living in Ballyhaskin 1863
However there are now 3 Hunters living in Donaghadee
Mary Hunter at ballymacruise in Millisle village
William in Donaghadee townparks, and in the High St Donaghadee, either the same person or two fifferent people.
Going back to Ros davies Co Down website for Hunter and then looking down for the parish column  for ‘donaghadee’  starts with
HUNTER   family   Donaghadee   came over from Scotland with Hugh Montgomery in 1603 as tradesmen to help build the port & town   HN
HUNTER   .   Donaghadee   a brewer for Mr Tomb; on a list of suspected rebels during United Irishmen Rebellion of 1798   MOA p256 {If this Hunter is yours, that’s a possible reason to emigrate as the trials and executions are stll going in the first decade of the 1800’s
Theres about 6 more entries and keep an eye on Ballywalter whitechurch Hunters
Switching to Houston or Huston in Ros davies where she files them together under Houston
Miss   Abigal   HUSTON Donaghadee   wife of George Burrowes;mother of Marey & Sera; died 16 Aug 1792 aged 36; buried Donaghadee graveyard   MIs Now that doesn’t turn up as a well known townland in Donaghadee 
If the family wrote back after emigration there may be material in 
http://www.dippam.ac.uk/ied/ PRONI is too big for me to tackle for you but I use their e-catalogue online often
Other underused sources include family history manuscripts eg at the Linenhall Libarary in the Blackwood Collection are volumes for 
HUNTER   2p96N Dunmurry, 16p3?4, 27N {not relevant its near west Belfast}
HUSTON   33, 52 Ballynagross {not relevant its near Downpatrick}
Nevertheless as you been brickwalled to rule out the volumes 16,27,and 33 might be worth clearing
I suggest you write to them asking them for photocopying estimates only if they think your knowledge relevant and be prepared to pay the extra for post and packing if you are tempted.  “The Library welcomes all research enquiries, whether made in person, by phone, fax, letter or e-mail. Enquiries from members will be answered free of charge. Visitors from afar, and in particular those engaged in serious research projects, are recommended to make prior contact with the Library to ensure that they receive the best possible service. More complex enquiries should be made by letter, fax, or e-mail. Enquiries of this kind from within the British Isles will normally be answered free of charge, apart from any copying and postage charges. A minimum charge of £2 will normally be made in respect of overseas enquiries. A4 photocopies b&w are 20p.  The Library may be able to assist those with more extensive research requirements on terms subject to negotiation with the Librarian. Contact the Library for further information on 
info@linenhall.com or Telephone 028 9032 1707. Their address is The Linen Hall Library,17 Donegall Square North, Belfast BT15GB, Northern Ireland, see their website for contact details or use Email:info@linenhall.com. My information might well be out of date.
 Which brings me back to church records Ros Davies is better than PRONI’s online guide to church records as she gives further locations sometimes
Wishing you luck , I am a Belfast exile, and travel is probably beyond me, but I would still love a weeks holiday in the summer in Donaghadee anytime
JimG