I'll admit, it's not that comfortable. But here are 3 inexpensive ways to instantly improve your sanity while riding over 350 miles/day.
1) Tech Spec Gripster Tank Grips
I have a fully stock set up on my 2003 Suzuki SV650S, as far as bars/seats go. One of the best $40 investments (I got a special price at the Tahoe Adventure Rally) I spent last summer was on a set of Tech Spec Gripster Tank Grips. You can see all 3 pads on my tank above. They're an absolute necessity on ANY sportbike. Not only do they help you grip the tank better but they just make longer rides a little easier. The more you can grip your tank, the better you can hold your position squeezing the tank. And if you've used your body position to lean harder, you know how important it is to have a solid place for your opposite knee. :D
They make grip pads for many makes/models of bikes and even sell the material in sheets so you can make your own if necessary. They come in two different compounds and the one I have is the "C3 Grip" ($51.95). They aren't just pads, to protect your tank, but they provide so much more comfort on a long distance ride. I have a much easier time holding my body in place.
If you ride a sportbike, why don't you have these???
Cost: Starts at ~$45 depending on the compound you choose. They're having a daily contest to get yours free, but it's not clear on their website or Facebook page as to how you can win.....
2) Seat Pad / Custom Seat
I forgot to bring my trusty sheepskin seat pad. How did I forget something so crucial??
A few years ago I bought a sheepskin pad from Alaska Leather Online. I didn't start using it until last summer when I went on a ton of long weekend trips, riding over 250 miles/day. I don't kno why I forgot about it this time! I just know that it would've brought me much comfort on this 990 mile weekend. For $65 your butt will thank you! At least, that was the cost for my bike. Since they don't make one specifically for the SV, the Pillion seat worked perfectly.
Where to Buy: Alaska Leather Online
Cost: ~$65 (for an SV, other bikes may vary)
3) Tank Bag
It seems obvious but having something right there for you to lean on is such a huge relief. Especially if it's magnetic. I can reposition the tank bag by shifting the magnets forward or back. Since I've only ever had magnetic tank bags, I'm not sure how else this would work with a strap mount tank bag since you have to preposition the straps. (this photo is pre TechSpec)
I usually stuff mine pretty full (not extended) but full enough for me to push forward so I can lean in. Here's another shot of the pic above so you can see how perfectly placed my tankbag is.
Also, if you're wondering about the vest I'm wearing it's from Spectrum Ultra Sports.