I have mixed a few thing in headphones and the project turned out fairly good. I checked it with my studio monitors the next morning and the mix was pretty spot on.
So.... if you have no decent monitors here is how I would recommend you mix in the cans.
Find a song that sounds good in the truck or car or home stereo system and rip it to a wave. Save it on your desktop.
Now, as you work on the project you are recording and mixing, add a new track to the project and drag a copy of that wave into the project. Mute the track for now. and... ALSO..... be sure this track does NOT run through the master bus, route it directly to the interface/soundcard so that any FX in the master on your project does NOT skew the eq in the reference track as that would negate any advantage to having the reference there in the first place.
Now simply record the tracks for your project as you normally would do. When you get to the mixing/sweetening stage..... unmute and solo the reference track from time to time to see how the EQ and feel of the reference compares to the one you are recording. Make adjustments to your tracks and busses as needed to attempt to get your project as close sounding as possible to the reference.
It's not the ideal way to do this but one must do what one can, given the situation.