like everyone said.. get some better tires and learn to drive in the snow. i rarely use 4wd in my ranger now that i put the duratracs on it.
secondly.. you do realize that if you swap to a 4wd drive train.. it would be the same as a ranger with your motor that was 4wd.. so your argument about gas mileage is invalid.. becasue you would just make a 2wd a 4wd.. and in all honesty..ive never noticed much difference between 2wd and 4wd trucks in terms of fuel mileage unless its a 4 banger.
thirdly. saying you cant afford loan or insurance etc. its going to cost a pretty penny to convert your truck to 4wd.. you can sell off your ranger and buy an older ranger and not have a payment..
EDIT: just noticed you said you would only get 5k for your truck.. its an 07. what the hell is wrong with it? you should be able to get double that at least
07 Sport, 4.0, 4x4, leveled, 265 Duratracs, exhaust, intake, tune, stereo
08 6.4 F-350, smoked mirror and cab lights, H&S, 5" Flo-Pro, No Limit/XDP EGR delete