Muttley, my 2 cents for what it's worth, bearing in mind Murphy's law states if you take tools you won't need em and if you don't you will need em
I'd grab a decent 1/2 inch drive ratchet and a 10, 12, 14, 17 and 27mm sockets (27mm for rear axle nut...arrrrr
). 10 and 17mm combo spanner or two wouldn't go astray.
Good set of pliers/side cutters/phillips screwdriver/roll of sparky tape and a few zippy ties. Spare fuses, couple of bulbs would round it off.
Still going to be a bit of weight in there but depends how much other gear you are taking and how far between towns on your trek. ( as in will you really need much if each town is only 20k's down the road )
( there is one other bit of Kit that someone found to be essential on the SoO 14 run last year but I'll say no more,
:wink: )
As for oil, I wouldn't bother. If you have a quick check every second or so fuel stop you will spot a drop in level, if you drop your oil on the highway there is a good chance that a spare litre isn't going to do it for you. If garage does not have your brand a top up of a good quality oil same/close to your weight (15/40, 20/50 etc) will get you through.
As said mate, my 2 cents, other may/will have better ideas and advice, thats the great thing about this forum.
Cheers