Thread resurrected? BBR your neti pot suggestion is a good one, you can also buy hypertonic nasal rinses in a pressurized bottle with a nose nozzle that do the same thing conveniently.

BUT, really, your best bet is to send the Midnight Roaring Snorer along to a sleep centre for a sleep study. I've been there done that. There are sleep centres in the public hospital system, or if you have insurance, the health fund covers like any other hospital admission at a private centre. Then, your darling man will be confronted with the degree of oxygen deprivation going on every single night & the likely health effects & they are more likely to want to get something done to fix it.

PS in my case, guilty as charged, however I only snore when I'm on my back and that's only briefly through the night.

ETA - and read that book with the breathing technique - it doesn't work for everyone but for a subset it does & it's worth trying.