Saggy Altura Seatpost pack - and mudguard recommendations

[ScumOfTheRoad]

I really like y Altura Arran seatpost pack https://www.leisurelakesbikes.com/bags-racks/saddle-handlebar-bags/altura-arran-expanding-post-pack-black__15302
The problem is is is almost sagging down onto the rear tyre of my new gravel bike. There is not a great deal of seatpost showing.
Anyone got ideas on how I can get the pack to ride a bit higher? The snap on 'flaps' have a lot of play in them - I wish it were adjustable.
I could try bending the frame, but I don't think that will do much good.
Ideas?

Oh - I should say I dont have mudgards. The bike is a 700C Marin Nicasio. I guess some mudguards could be a fix.

[zigzag]

there is a contour saddle rail mount, that raises the bag higher.

[ScumOfTheRoad]

Much ta zigzag. I have a new mount on order.