Oh yes, very fair! If the trade off you were offering was spooning, long discussions about your relationship or a trip together to an embroidery convention that would be a different matter. But, this is an amazing quid pro quo.
The fact is, not all guys like the anal thing anyway. But even if this was something your guy really wanted, trust me, guys will take what they can get, not unlike dogs or pigeons.
Crystal ball - you are going to do just fine.
This will probably followed by a long string of "please contact me @..."
lol
As long as he's getting as much as he's giving, it's all good. At least that's how I role. My biggest turn on is the woman getting turned on. The more she is, the more I am. So it's in my best interest to (as Eddie puts it) make her go "wooooooooooo". And in my experience, when they go hog wild like that, it becomes really fun. ;-)
If he's insistent, then just tell him he's not getting jack. You'll see how fast he turns around. lol
Sounds like you're offering a helluva deal. Got me sold, that's for sure!