I've done a fair amount of long distance riding on my Enfield and had a fair amount of trouble -- only some of which was due to my newbie status. You can look me up on the forum if you want to know details.
Now that I know the bike fairly well, I carry a sizable tool pouch on long rides. (It's about the size of a shoe, and I tuck it in my saddlebag. It's not that I want to have to use it, but it's turned out to be helpful.
Here's what's in it, in order of importance:
Electrical tape
Loctite
Several cable ties
Regular Phillips screwdriver
3/8" ratchet set 8mm to 17mm
Long socket that fits spark plugs (13/16" I think but don't quote me)
Combination wrenches 8mm to 17mm (with doubles of 13mm and 14mm)
Spare spark plug
If I were going for more than 48 hours I'd probably take spare tank bolts/nuts too, since mine have wiggled off.
I've found that my effective speed, including stops, is about 40mph. I try to go faster but it never really happens. So now I plan my range based on that.