I've the same predicament and considering either a concealed awning rail in roof gutter with cut outs (VW T5 Bolted Awning Rail VW Logo Roof Rack – Camper Essentials) for the VW roof racks or a Reimo/Vamoose railThere is a nice rail which fits in the roof gutter, but I have a set of VW roof racks (across not inline) and installing a rail might prevent me from being able to pop them on and off as I like.
I remember the time I watched Caravans drill into a van to fit a rail, and thinking the same as you.
All the best with your new rail.