Hmmm, if you got a vehicle that can handle some moderate off roading (you'll need good clearance, Suby, truck, SUV) there is a ton of free camping just outside of Idaho Springs going towards Mt Evans. There are a ton of access roads on Forest Service land around there. You can just find a nice clearing and camp. No water, toilets, that sort of thing, but it's free. Bring your water and a shovel.
There is also an RV style campground in Idaho Springs. I think most of the forest service campgrounds which I think are about all located in Summit County or Winterpark are probably still closed due to the fact they are covered in snow. You could call the local Forest Service office, they'll be able to tell you what is open and what isn't.