Towing 5K will have the sump temps up pretty high. And he'll be spinning the motor down a gear, or two, on any grade at all. Plus the 'Finder has a small'ish sump to start with. Not the best combo for robustness.
1st I'd find an oversized WIX/Napa Gold filter if it uses a common spin-on (?), to add a bit of total capacity to the lube system.
Then I'd look for Chevron Delo 15W-30 Severe Duty (SD) oil. At least you have a 15 grade as a minimum as all Hades breaks loose (heat) on a long up hill pull. Very stable and durable multy.
I'd also add a tranny cooler and make sure you have fresh tranny fluid as the summer starts.
Change to all-metal, all -season coolant and make sure the hoses are in good shape.
Have fun, but be sensible about long uphills. Don't try to keep up with everybody ...