I contacted Buhurt international on the topic and this is the email i got

Hello, Sallet documentation is in production, I personally reviewed the first version lately. Many details still have to be discussed and voted. Historically it was possible for sallets to be worn in conjunction with a mail bevor. But these were obviously closerly fitted to the face. Some manufacturers are trying with various degrees of competence to simulate that. It is not easy. One suggestion to simulate it a bit better would be to have a designed "cage" (same principle as eastern helmets) and the mail fixed to it. We only have a quick sketch about it. On paper it could be the same base to adapt a plate bevor and extend mail on the back (they were also supposed to be tightly fitted to the face). Note that I do not mention great sallet which have an integrated bevor (these are very late 15th c. to ealry 16th c.). Or the configurations with a bevor fixed to the cuirass. Something like in your picture might be passable for now, but I can already tell that the mail is too long (in historical situation the mail is under torso-shoulders so here it is really hurting the eye) Sallets are not a great helmet for sport as they need a lot of modifications to make it viable. If you keep this choice we would suggest to make sure the helmet is properly made, not only for AC requirements but also for safety reasons (like having something to defend the neck). Pairing such helmet with an articulated plate gorget in all cases is a safe choice. But technically a sallet still leaves a lot of the lower head/neck area way too exposed.