Repeating theme here...use tow/haul always, let computer figure out uphill gears, select which gear keeps the pace you prefer downhill.
And your 3 mile hill climb will probably be over before you know it. I have 2 20+ mile climbs coming up on next trek out in 105+ temps. We will be pushing Clifford hard but not too worried about it.
2014 Stealth Evo 2850- "Woodstock"
2011 Toyota Tundra Rock Crawler TRD 5.7- "Clifford"
2013 Honda Accord Coupe V6 w/Track Pack- "Julia"
Just glad to get away