If the husband and wife both agree, can they do anal and oral sex, or even torturing kind of sex like caning?
Is it immoral?
If anal sex is safe, then it follows that you should not need a condom for protection. Also if anal sex is natural, you should not need any artificially processed lube, since nature will have made natural provisions to reduce friction. Once you start adding artificial prosthesis, then natural can be ruled out. It becomes a staged choice that works due to addenda. The game that is played is like saying, I can go into a combat zone, because it is safe. Then I put on two layers of body armor, and tell you not to pay attention to the prosthesis, and then reaffirm that going into a battle zone is very safe. Some people will just accept the illusion.
The way I look at, all forms of sex between a consenting husband and wife, is OK, if they both agree. Often more variety is needed, when sex is not longer naturally spontaneous. Then you may need gimmicks to trick the body, with grouse satisfying for many, due to the needed overcompensation. Ultimately, a good positive feeling and attitude, between husband and wife, goes a long way to the needs of their team.
The only restraint, I see is, don't ask and don't tell, what you do behind closed doors, since this will create problems for yourself and others. Not everyone will be cheering all things, if you make them look in your gutter. Most people are not looking in the gutter, when they meet friends or new people, until someone focuses their eyes in the gutter. Then problems can begin. Once imagination is confirmed, the stage changes. Why create problems?
Too much revelation is the downfall of the LGBQ community. If they went about their sex lives, in private, they would be treated more like everyone else, since most people's mind don't go there, unless led. But for some reason, this community likes to waive their privates in peoples' faces. Most straight people do not wear their sexuality, like clothing for all to see, unless they consider themselves a player. A player is not someone you can trust to be honest with you, or with themselves. Often the player is at the gimmick stage which means they are leaving natural and need your approval.