- welcome to TM Herve

I don't know if it is much help as I have a Series 1 Aero 8; this has
no height adjustment, only forwards and back!
Assuming your later Aero is the same, it is fairly easy to remove the seats (4 bolts to undo).The space is a little constricted when getting to said bolts, but it is doable.
Once the seat is out ,it should be fairly simple to create e.g. a couple of wooden spacers and perhaps longer bolts, to raise the seat height.
James