So this epoxAmite appears to be just a particular formulation of epoxy resin. So yeah, it works.
I haven't seen the Bondo Jelly resin sold in stores, that should work just fine without needing to thicken it. The reason for thickening the regular resin is so that it will build up more quickly. Otherwise, it tends to self-level into a thinner layer so that you have to apply multiple layers, which can be a pain when you have to mix up every batch separately.