Planning help: Leeds to Exeter to Oxford

[Kilopylae]

My friend has got himself into an 'interesting' predicament with a need to pick up camping supplies from Devon and has turned to me for help with finding him the cheapest route to do the following:

Leeds to Exeter, depart Friday 1 December
1 hour at Exeter St Davids or 30 mins at Exeter St Thomas
Exeter to Oxford, arriving before 9:30 AM on Saturday 2 December

He can overnight in either Exeter or Oxford, but would prefer to be able to complete the triangle on Friday and get to Oxford that evening.

He wants to do this the cheapest way possible and "doesn't mind spending the day on public transport". He holds a 16-25 Railcard, no Coachcard or anything like that.

The "default" starting fare is £62.95, generated for me by Trainsplit with an itinerary of Leeds - Kings Cross - Paddington - EXD - Bristol TM - Didcot - Oxford:
Leeds to Wakefield Advance
Wakefield to Doncaster Advance
Doncaster to Grantham Advance
Grantham to EXD Advance (I've noted this one for its good value before!)
EXD to Bristol TM Advance
Bristol TM to Oxford Off-Peak Single

Edit: In the real misery-inducing category is also the option of doing it for £38.27 by taking a Flixbus from Leeds to Exeter for £14.98, arriving 20:55, and then Trainsplit will do the 6:27 Exeter to 9:15 Oxford for £23.29, or a bit more if he takes one of the slightly later ones.

Can anyone help me do any better?

 

[mangyiscute]

I can't see anything much better - only things like perhaps taking a Northern train from Leeds to Doncaster could make that section slightly cheaper, but its very diminishing returns, or also on the 6am out of Leeds direct to Exeter there are some cheap fares but that is very early.