I would maybe load what you will haul most often and check for the location of your e-track to make sure it will work well. I have an 8.5' wide v nose that was set up as a car hauler so the e-track is in a little over a foot from the edges so that it lines up with typical track width of a car...
I think I will have the same problem this winter. I started looking at McMaster-Carr, they have quite a few options for the seals and the prices don't seem that bad.