Agree place of birth looks like Redshires on Margaret's birth, I also looked through a number of the births and baptisms for her siblings and they give slight variations of this Red Shear/Redsheer/Redshear etc. All the births I found are registered in Bridgetown sub-district of Wexford (town) registration district, and the baptisms in "Piercetown & Murrinstown" Catholic Parish - these help to narrow down the general area as being abt 6km south west of Wexford town (see attached maps).
As this place seems to be a local name I checked the OSI maps for this area, but found no matches - some local placenames are shown on official maps, but many are not... The same placename appears on baptisms and civil births for a number of other families, so seems to be a well known.
I located a very promising reference in "The Origin and History of Irish Names of Places", by Patrick W. Joyce, 3rd ed., Dublin 1871 which reads as follows :
"...There is a gap in the mountain of Forth in [Co.] Wexford, which... is also called Reed-shearde or Red Gap, by the inhabitants of Forth and Bargy. ..." (see attached extract)
The Forth Mountain is located close to Murntown/Murrintown, and there's a second clue in the name of a road running north west of Murrintown a "Redshire Road" - these clues combined all fit the description, civil district, parish and general area and a good match to where your Duggan/Doyle family lived. See Google maps route from Murrintown.
I double checked along this road on the historic OSI maps - but found nothing marked to show RedsheerRedshear. Most of this road runs through a townland named 'Forth Commons' (Kildavin civil parish, Forth barony), I've included an extract from the c1840 OSI map.
Griffith's Valuation, dated 1853, for this area show a substantial number of properties at this Forth Commons townland (two other townlands of the same name in Co. Wexford) it's shown as 'Free' so no immediate lessor/landlord - I had a quick look and didn't spot any Duggans, but there is at least one Doogan, and also a Doyle...