I have replaced the sale view with my own using this method:

<record id="sale.view_order_form" model="ir.ui.view">
    <field name="name">acu.sale.order.form</field>
    <field name="model">sale.order</field>
    <field name="priority" eval="100"/>
    <field name="arch" type="xml">
        form...
    </field>
</record>

I kept all the original fields in order for other xpaths to work, and kept them in a very similar structure. However i have now noticed once this view is installed i can't update the sale, sale_crm or sale_purchase (probably any others which require sale).
update log:  pastebin.com/YHxsa3HY

The only solution I have found is to add a dependency of my module to e.g. sale_purchase, which is less than convenient.