Enamel base, then Future, then oil or acrylic wash?

Sounds like you have a good understanding of the wash process. When using Future as a acrylic clear coat make sure it has cured at least 24 hours and is applied heavy, Future is self leveling and can be brushed on with no build up or brush marks.

When using a oil wash over the cured Future work quickly! Many here recommend a 'milder' thinner that is less aggressive than most thinners.

*Best to simple paint a scrap model or plastic using the same techniques you plan on for your model, this way any errors can become learning experiences without the frustration and expense of sacrificing and model kit.

If you cover the enamel base coat with future, it will protect the base coat from the thinners from oil or enamel washes.  You should be fine.  I prefer oil washes over acrylic washes anyway so I do the same thing.