For what it's worth the Cessna 182 is a fairly popular tug aircraft in South Africa.
I know of a private operator and two clubs nearby who tug using unmodified 182's in similar hot and high conditions as Nephi.

Magalies Gliding Club operates a 182 (not sure which variant) tug at 5102 feet MSL in temperatures up to about 95 degrees Fahrenheit (35C) on a 5000 foot grass runway.
The grass increases the rolling resistance significantly yet the 182 is still adequate for tugging the heaviest ballasted, twin seaters in such conditions.
The club's 180HP Super Cub accelerates faster (probably due to less mass) but battles to climb at a safe speed when tugging heavy, ballasted gliders.

Pros:
- The 182 is more marketable should you wish to sell it later.
- Spares are usually more plentiful (especially around my part of the woods).
- It can be hired out during the week to cover costs while the club is not using it. There isn't much of a hire and fly demand for a Pawnee.

Cons:
- Price
- Expensive to maintain and operate (compared to a Super Cub)

The 182 is very thirsty compared to a 180HP Super Cub so much so that a single tug rate is charged and the club's Super Cub cross subsidizes the 182.
I can try get the fuel burn rates from our tug pilots if that will help.

Now a winch launch on the other hand ...