They aren't going to monitor everyone's trades.
But the safest is probably staking it all. Because stakes are so random and goes around its the best bet
Works for both f2p + p2p because both have duel arenas now.
But I do direct trades, and it always works
Just add the person's user to friends list before the trade, say you were just helping out a friend if you get caught by Jagex (which is very unlikely to happen anyway)