Like others have stated, the 4.8L in your 1/2 ton is not up to the task of pulling anything but a really lightweight 5th wheel. I would just get another TT in your shoes IF you're not wanting to buy another truck.
We went from an 8500# 28' t.t. to a bigger heavier 5th wheel and got one and a half mpg better. The old F350 is enough to pull either one though with out too much effort. I guess the 5th whl. is more aerodynamic or something. It might have something to do with the way the 5th whl. fits up to the back of the truck closer.
a 4.8 liter engine just not enough for most any tt or 5ver. better to have too much than not enough when it comes to truck.I`ve pulled from an open car trailer, to a 19 ft.TT, then a 31ft. TT and now a 36ft. 5ver. and pulled with a 4.8 liter 1/2 ton, also a 5.3 1/2 ton. any TTs will over work the transmission if your not careful when using a 1/2 truck. a 3/4 or up truck will handle 5ver much better.
just My 2 cents
2006 GMC 3500HD CCSRW4X4 DURAMAX Allison EDGE EVOLUTION tuner
2012 Keystone Avalanche 330RE 5th wheel 4 slides
statements in this post should be considered opinions and not facts
aruba5er wrote: I think the TT is much easier to back up than the 5th wheel. The pivot point is differant and the TT is more responsive. I could back into the space along side the house in one shot. Now because it take so long to turn I back, go forward, back some more, drive on the grass, swear, go forward back up and finally get it in place. Life was so much simplar with the TT...
For a second there, I thought I was reading something I wrote. I had my wife read this so she knows it's just not me.
I have to back our RV across the (well landscaped) yard, to get it on the other side of the house opposite the driveway. First time I cursed like a sailor, then cried like a baby. Thank God bermuda grass grows back fairly quickly.
If there's a learning curve to this 5th wheel backing thing, I haven't pulled out of it yet. But I'll get there.
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. I speak from my own experience, take or leave it. Good advice is being offered here. 
