Depends on whether you want to be certan you never exceed any of the tow vehicle's (TV) weight limits.
On a half-ton pickup, the most likely weight limit you'll exceed with even a small 5er is the GVWR of the truck.
Load your truck with everything that will be in it when towing, including the 5er hitch, Mama and the kiddos, Rover and the puddy tat, toolbox, other stuff, full tank of gas. Weigh the wet and loaded tow vehicle on a CAT scale. Subtract the gross weight of the wet and loaded TV from the GVWR of the TV. The answer is your max hitcch weight without being overloaded.
Divide that max hitch by 0.18 to get the maximum GVWR of the 5er. Don't kid yourself. Use the GVWR of the 5er. If the GVWR of the 5er is more than your calculated max GVWR you can tow, then don't buy that trailer.
Do the math and you won't find very many 5ers with a GVWR low enough that you can tow them without being overloaded.
Example: I had an F-250 diesel TV and a 25' 5er with one slide and 7,900 pounds GVWR. That small 5er usually overloaded that F-250. So it would have overloaded an F-150 even more.
Caveat: If you special-order your half-ton, you can order a heavy-duty payload pkg that may let you tow a small 5er without exceeding the GVWR of the TV. For example. 2012 Ford F-150 with EcoBoost engine, 3.73 limited slip axle ratio includes the HD payload and max tow pkgs, and has a GVWR of 8,200 pounds. You should be able to tow a trailer that weighs up to around 10,000 pounds without being overloaded.
But that's a very special F-150. Mine is more typical. My 5,000-pound TT puts me just over the GVWR of my TV when wet and loaded on the road.
Grumpy ole man with over 50 years towing experience. Now my heaviest trailer is a 7,000-pound enclosed cargo trailer, RV is a 5,600 pound Skyline Nomad Joey 196S, and my tow vehicle is a 2012 F-150 EcoBoost SuperCrew.