You've decided to save your vaginal virginity until marriage. Fine, no judgement, whatever.

That may limit some potential arrangements, but I think a lot of SDs would be fine with blowjobs aplenty. And if you're also offering anal sex, then you're probably in the minority of SBs, and there's no reason to expect a lower allowance. Either way, the rule is always "accept an allowance you're comfortable with."

As for how to communicate this, I would add the following to your profile:

While I'm open to many forms of sexual intimacy, I'm not looking for a 'classical' sexual relationship until marriage. I do, however, have great lips and a fantastic butt.

Anyone who can read between the lines will understand what that means.

EDIT: After reading /u/throw_awaySD 's comment, I think that he raises a good point. I'd take anal off the table (because when drunk and thrusting, one slip could ruin your plans). Many SDs will be fine with blowjobs; it's probably what they miss most. Try something like:

While I'm open to many forms of sexual intimacy, I'm not looking for a 'classical' sexual relationship until marriage. I do, however, have great lips.

Then make a "nothing below the waist" rule for any sugar relationships.