I don't think option trading not on full, liquid exchange can work well.  
Selling options is shorting volatility (a bet that implied vol will be higher than realized vol), which needs to be hedged. On exchanges, hedging automatically provides collateral, ie. sold atm call option for 1 btc is perfectly hedged by a ~0.5btc long, so even at impractical 100% collateral, you only need 0.5 btc more. The total is always 1btc.

On a purely options exchange with 100% collateral, you need 1 btc + enough collateral to go long 0.5 btc on another exchange, and in the worst case, enough to go long 1 btc. That's two times more expensive and requires additional hassle.