Ok, bit of a strange idea and not sure if it's doable. If I don't explain it well enough, read it again and then ask me to rephrase it
Read it ALL first btw
-Remove all ladders apart from the small wooden ladder
-Bump its price to 1000
-Make it need reparing
Then, each time you heirloom the ladder you get the next equivilent one
So
Small Wooden Ladder --> Wooden Ladder --> Medium Wooden Ladder --> Large Wooden Ladder --> Siege Ladder
If this requires less work than making them take up two slots etc and all the other ideas for them, I think it will balance them out
Because if some moron uses 4 heirlooms just to get a Siege Ladder he should be allowed to use it
