I have two long fence lines where I will be planting 4 trees along each.

Fence line 1: trees will be spaced about 30' apart

Fence line 2: trees will be spaced about 25' apart

Material is as follows:

2 silver maple

2 single stem paper birch

2 sugar maple

2 trembling aspen.

All trees are about 15' tall with 50mm calipers.

I was thinking about alternating between silver maple and trembling aspen along one fence line and sugar maple and paper birch along the other fence line.

How would you distribute this plant list?

Seems like a good set-up.

Silver Maple and Quackig Aspen are both fast growers.
Sugar Maple from my experience have been slow growers, and Paper Birch are not speed queens either.

Especially on the Sugar Maple make sure the roots do not circle and kill the trees when you plants.