You've been listening to the wrong people then.. I'm not talking about breaking in in below freezing temps - but 50F for ex. is fine.. Colder than that, or less than say 45F and it's just not fun to be outside that long anyway.. Basically, the colder the outside temp, the more crucial preheating is. I personally wouldn't break in an engine without preheating if it weren't warm outside. AFAIC though if it's 80 out, and you wrap the head, you can break-in without preheating if you must - though yeah preheating would be better. If it's cooler, preheating negates the wear of starting an overly cold engine and compensates for colder outdoor temps..

And you don't need a lipo by a long shot. I've been using the same Losi Spinstart for seven years, and am probably on my third 7.2V stickpack. Both my starterboxes also have nimh stick packs. Keep them charged and they're fine. A freshly charged 3000-3700 nimh stickpack will last a day's break-in session no problem.. I've broken in all kinds of engines, in all kinds of temps, and they've all been fine. An expensive race engine would be a bit of a different story, as they tend to have a lot more pinch at first - so preheating is more important, etc. So they take a bit more work generally. Force, LRP/Losi/Dynamite/Mach engines etc.. are a piece of cake in comparison(mostly though because break-in doesn't last nearly as long..) And 50F is fine. And you don't need a lipo....

You're making nitro sound harder than it is. And it's not. Half of the supposed "difficulty" of nitro is just in peoples' heads. It's made out to be more than it is. As long as it's 45F or above, wrap the head, preheat it up to 200ish F, and run some fuel through it without going crazy. Complete cool down at TDC. Repeat...