depending on how big you want to go, a new 5th wheel will run 40-80k, plus the cost of the truck to haul it with, and a half ton is not recommended for 5th wheels
If it were me, I'd go with a motorhome, tow your current vehical behind it, park it where ever you want to sleep that night. Yes, the cost will be higher to buy the motorhome.
Motorhomes are easier to sell than 5th wheel trailers, guy down the street from has had his up for sale for 3 years, very few people own a truck to tow a 5th wheel with, let alone those who have a 5th wheel hitch.