Re: warm enough for straight veggie now...
For a couple hundred bucks you can make a system that will work okay in warmer climates. It's all about startup. If it was 40F last night your fuel will be at that temp, or just a little over, in the morning when you go to start it up. Even if you mix it, it may settle out and be hard to start in the morning. If it's 80F at night I wouldn't worry about it so much in the short term. IMHO though you might as well make a good system so you don't have any issues and can then drive in any climate without worrying. And even if it does work in the short term, if not heated very well and therefore more viscous than ideal, your stressing your pumps and injectors more than they were intended and thus shortening they're life. Spend the money and do it right, you'll make back the investment in no time. I made mine back in my first trip back east.
1989 TC 2000; 235,000miles; 5.9 cummins with Alisson 545; Straight veggie burning with onboard filtration. Converting to a Toy Hauler for the summers racing motorcycles.