You REALLY should stick to the MANUFACTURERS OEM tire size and style choices.. If you want to move from P to LT tires, choose wisely and don't over choose, a "C" load rating would have well exceeded a 1/2 ton capability by around 1,000 lbs on the axle and it would have done that with 45 PSI.. The E load rated will most likely need around 60-65 PSI to be near the "C" load rating..
I'll have to disagree with you, p rated tires are good for like shopping and light use. LT tires are much better suited for towing, or hauling stuff and will give less feel of sidewall roll when towing. Tbh ,I think 1/2 ton trucks should come with LT tires on them. Not nessassarly e load but something better then p tires. You kind of eluded to that in the post. But to say stick to the crappy oem p tires isnt great advice.