Seriously dude get a sleeping pad. You can have as warm a bag as you will, but it won't do a thing compressed under you. Cold will come straight through from the ground. If you aren't in the cold yet, you will be eventually.
Inflatable pads are for camping trips, when you rarely need to throw it down over thistles rocks or glass, and if it pops whatever, repair it at home. Get a solid foam mat. If you can put down $30, get a Ridgerest pad. If you can't, you can get cheaper heavier things or probably improvise it for free. The ridgerest is bulky, but nearly weightless and will last until you lose it or accidently set it on fire.
If you have the right sort of straps on your pack, you can attach the rolled up pad in a way that props up your pack, and turns it into a solid backrest when you sit down, which is pretty damn nice.
As others have said, worst thing to skimp on is your camp stuff. It'll be your home. On a camping trip you can rough it then go back to a house have a shower sleep in a bed. If you're living out of your pack, really do your best to have some comfort, since it's all you'll have.