Fords altitude towing recomendations

I live almost at sea level but my most common destinations require 3000-4000' passes which are within 75 miles of home. Between spring and fall I can cross the mountains twice a month. It's not until winter sets in and the chance of chain requirements keeps me in the lowlands or on the coast. Usually twice a year, trips take us on passes over 5000' - This year we did passes over 11,000' without issue. Loosing 10% of my engine's performance would be slightly annoying, losing 20% might be the difference between making a trip enjoyable or stressful, but losing 40% of the engine capacity might make things unsafe. I don't think I would find an impassible grade, but I cannot believe the engine struggling in first or second gear to keep the load moving is how I want to spend time on any portion of road. I stayed with a diesel to get a large engine with forced induction - If the ecoboost had a 6 liter model, I possibly would be driving a gasser again.