Part of your tire changing difficulty may be in technique. Do you squeeze the tire beads together all the way around the rim as you remove the first bead? On tougher tires, I do this repeatedly as I pry off or on, and seldom need a lever. When you do need leverage to remove, try two plastic levers about 4 inches apart, and pry both at the same time.
And/or your rim strip or tape may be part of the problem. Try a thinner strip or tape, or narrower if it's interfering with the bead seat.
The other day a co-volunteer at the non-profit shop brought in a 30-year-old wheel he was refurbishing, but complained how difficult it was to change tires. It had thick fabric tape covering both bead seats. I put a new rim strip on and the 30-year-old problem went away.