« Reply #3 on: Friday 09 February 18 10:12 GMT (UK) »
sorry, I don't see a link between being able to write your name and ages of spouses. Someone signing with a mark may have learnt to read, just not to sign their name. They might not have had the chance to learn if their family could not afford.
Susanna may have been older than James, it's not unusual.
The 5 year old being baptised in Camborne is tempting, but there is James Skewes marrying in Camborne in 1789.
It might be worth trying to trace each of your candidates, marrying them off and finding children to check for family names.

Cornwall: Allen, Bevan, Bosisto, Carnpezzack, Donithorn, Huddy, James, Retallack, Russell, Vincent, Yeoman
Cards: Thomas (Llanbadarn Fawr)
Glam: Bowler, Cram, Galloway, James, Thomas, Watkins
Lincs: Coupland, Cram
Mon: Cram, Gwyn, John, Philpot, Smart, Watkins
Pembs: Edwards (St. Dogmael's)
Yorks: Airey, Bowler, Elliott, Hare, Hewitt, Kellett, Kemp, Stephenson, Tebb