I insulated the windows, taped windows with some R3 from Home Depot, serves double duty by blacking out sunlight coming in and keeping my lights inside concealed from prying eyes at night. Had someone roll up on me last night, probably running my plates.
I know all to well about the carbon monoxide poisoning and the stove does heat the unit up well, I notice there is a moisture problem from the breath in the confined space of a 10 foot travel trailer. If its really cold, I will crack the window and with a little 100 hour battery fan on 2 recharable AA's, and stove on low.
The sleeping bags I snagged from Waltons for $8 are great, might go back and clear him out of his stock. They are little 1.5 pounders rated at +5C, tripled up they are super warm.