So on my adventure around town today I found that nobody had a relay to my likeing for this little addition. On a whim I stopped by the dealer, who I've found to be generally pretty knowledgable and helpfull. Talking to one of the guys in the parts/service dept. he seemed to think that the voltage at the energizer wire wasn't critical, saying that even down to 10.5 volts should activate the starter. His suggestion was that the contacts on the starter may be just close enough to the outer limits of the tolerance that the temperature affects a good contact, which could be the case, though I'm skeptical for several reasons.

1) Doing the same thing on a 40 degree day that it did on a 90 degree day and if the tolerances are really that close I'd expect it to give me more trouble on a cold day.

2)After it starts cranking (after several clicks), even if it was half a revolution, it will crank reliably the next time I try.

3)There is definitely a load on the system when it clicks, though I haven't tested how much yet, I need to hook up the multimeter properly to see what is going on for sure. Basicially if you try to start the truck without the clutch in or the safety cancel, the voltmeter lowers a tiny bit, but in this case with the safety cancel engaged, it drops significantly.

Of course, one potential answer to the second point could be that the contact and flow of energy through the contacts is heating it up enough to bring the clearance back within spec if it really is just barely off.

At this point I see no reason not to put in a relay anyway, can't hurt, so I'll probobly do that when I can find a good one. If it continues after putting in a relay I would suspect the starter, which luckily I can get a brand new OEM one for $114 if it comes to that.