Bickepacking saddle bag touches rear wheel on mountain bike

I am planning a 2 weeks trip following a mountain bike itinerary consisting of 650 km including single trails and 25’000 m of positive (and negative) elevation.
I planned to go with my full suspension mountain enduro bike and I got the Ortlieb seatpack 16.5L and handlebar-pack 15L to pack all the camping gear. During the test ride last weekend, I was pretty pleased to be able to pack everything I needed in those bags.

The issue is that while riding on single trail going downhill, I was forced to keep the rear suspension to its tightest setting and even then, the seatpack was touching the wheel every now and then. Here is a picture of the setup:

The bike is a Canyon Strive with 29in wheels.

So the question is: how to avoid having the seatpack touching the rear wheel when going downhill ?
Putting the saddle higher is certainly not an optimal solution has it’s already too high to be really comfortable going downhill. I was thinking about maybe switching the rear wheel with a 27.5in but I don’t know how easy it would be and if it would be comfortable to ride for 2 weeks.