I am a Xdeep fan but Finn Sub has really good quality stuff, one of those wings can be used with conventional backplate and harness setup;
www.finnsub.com
www.finnsub.com
Also Halcyon recently made their SM rig.
SPELEO — Sidemount Wings | FINNSUB

FLY SIDE — Sidemount Wings | FINNSUB

Also Halcyon recently made their SM rig.