What Light Camper to Buy?

Hello, all! A newbie here! I have had my 2004 Tacoma 4cyl, 2WD 5spd since it was new, and love it. It now has a camper shell (just to haul around boat stuff secured in the back, and to be a trunk -- no facilities for human habitation).

I am getting closer to the time to be able to get long weekends away, etc., and want to do some 4-day weekend (or longer) traveling. I live in the Central Valley of CA, but would be taking trips into the Sierra Nevada, and need sleeping space for AT LEAST me alone, but better a Queen bed for me and the wife (who now is less inclined to agree to travel w/o accessible phone, full bath and WiFi, but I hope I can convince her).

We also have a 28ft sailboat, so we are both used to living for awhile in small spaces. (But in the boat we are in marinas most every night with all that stuff.)

I will be doing some of the travel on dirt roads, in the Sierra at up to 5,000 ft elevation, with springtime puddles up to about 6-10" deep, so a very lightweight cabover camper is what I'm thinking about now. Of course, each time I wanted to use it, that would require removing the current shell, and re-fitting the cabover in the Tacoma Bed. And I haven't been able to find anything affordable with all the accoutrements.

A towable (but not a canvas-sided Coleman-type) is also in my scope, and would be easier to get on/off as I might not then have to remove the current camper shell, but I'm concerned about the dirt road stuff. Also, overall weight is a concern, especially since I have some 6-10% slope climbing to do on dirt roads at 5,000 ft in the Sierra.

My budget is about $3-5K for a used unit. I can spend some time (and have the skills) for light rehab. Any thoughts? Is this a "No-way"?

Thanks! Peter