I offer anal, at no extra charge.
The ones that do ask for it, imo, have been very aware of the difference in penetration. They've either taken it very slowly and asked if I'm ok, or they've let me take full control.

The trick is LUBE LUBE LUBE!

I am the same, I don?t charge extra for it and I get lots of guys who have not tried it before come and see me. I explain to them to not go all the way out and then back in again as it just traps air in there making it uncomfortable (Also can be an embarrassing if you don?t want to fart like a trooper!), I have to go on top at first so that it?s easier to get in (do reverse cowgirl if you want to give them a better view) and a shit ton of lube. I spend a lot of money on lube 

I don't do anal, but I think any decent standard should be OK - though personally, I wouldn't use Durex. I had some EXS ExtraSafe and they were like gardening gloves! My guess is plenty of lube is actually the key issue to avoid splits.