You could try the private Monte Krah school. They do off-piste half or full days. Unfortunately the website is all in German, but the link below will give you a contact email and idea of prices.
There used to be this outfit too: Helli Team Bedarfsflug Not sure if they are still operating, but I’ll see if I can get a phone number for you. Schaldming, although not known for it’s off-piste, is a nice resort and there are good opportunities for some gentle off piste - one notable area is on Reiteralm. Hauser Kaibling has some too.