Good luck with Margaret in the church records.The only items I have found are sponsors to other Troxell children, so not much help.Based on John's birth date of 1736 in the Egypt Church Records, and the date of his family's move to Maryland in the mid-1750's, he was almost certainly married in MD. and the records are just not that great at the time.
In terms of public records, there is nothing in the will records, probate records, Equity records, burial records, etc.
All that I found is the following:
1790 census listing showing 1 male over 16, 3 males under 16 and 5 females.
Listing for a John Troxell who signed the Oath of Allegiance in 9,000 Men who Signed Oath of Allegiance (Bettie Carothers).This could be John, son of Peter or John, son of John Peter, no way to tell, but this is more likely John, son of Peter.
And the following deeds which are available online.Go to midmarylandroots and follow the links.
J:978 (1764) earliest Troxell deed found in Fred. Co. Records. L:379 (1768) N:48(1770) P:92(1772) P:540(1773) WR-2:41 (1779) WR-8:581 (1789) WR-10:198, 250, 252, 253 (1791)These are the last deeds for this John and wife Margaret joined some of these deeds.Richard Troxel states John moved south and is found on tax rolls in 1787 but I think he has the wrong John, perhaps a son.
Remember that John (the miller) and his father John Peter did not move from Gwynedd to Maryland until 1777.See MD. Deeds RP-1:89-92