How does that top case work out for you? I need a tail bag or case with backrest. Not sure what to buy.
There are all sorts of answers here in this sub-forum.
https://www.yamahasupertenere.com/index.php?forums/luggage-bags-cases-panniers.69/
For the Gen1 Tenere when I commuted into the city daily, I used a Givi 52 Liter Maxxia and needed to make a base plate to move it back far enough for my passenger. She loved the backrest but not the ridge in the middle of the box and the accessory pad would have meant moving the case even further aft. The white line beneath the case is the HDPE plastic cutting board used to move the case aft and it looked a bit like an AWACS airplane with a big radome.
For the Holan Nomada on the Gen2 Tenere it bolted to the accessory top plate. It could have been a bit further aft but she hasn't been able to ride anymore so I've left it. (Age related neck issue.) This is the 25L and I love it. Just big enough for helmet, vest, gloves, compressor, and small tool kit when parking on a curb downtown daily.
When not needing the big box a smaller Pelican sits there.