There are several forums/sections that get very little activity:
1 page in the motorcycle forum is 5 months worth of posts
1 page in the Schumacher R/C Superstore Support has 9 months worth
1 page in the IRC Racing Support has 9 months worth

and is there a sub section for every brand of gas/nitro motor?
1 page in the Fuji-Imvac Engines Support has 9 months of posts
1 page in the Quadra-Aerrow Engines shows one whole year

surely a vintage section could do as well as some of these