[Shop-talk] Gutter on metal roof

[Matt]

I added a lean-to overhang off the back of my shop recently and am considering
adding some form of gutter.
I have 2 objectives:
Stop the erosion where the runoff is cutting into the ground.
catch the rain for reuse.

It is pretty standard steel roofing, with about a 2' overhang from the nearest
support.

I was initially thinking plastic, but I am trying to strike a balance between
light weight, cost & durability.
Aluminum is probably lighter, but what about dissimilar metals?

I was just going to use one of the 230 gallon caged tanks that are becoming
ubiquitous as a collector.
Oh yeah, I gues I will need to consider the unusual - but not unheard of
snow/sleet load!

What are the chances someone on the list has already devised a clever
solution?

TIA,
Matt in Georgia.