securing sleeping platform

Hows it going everyone. Question for you guys with a sleeping platform in the back of your truck. Im about to install a platform in the back of my truck for sleeping. Im not going to go all the way across, and was wondering how people secure their platforms in the bed of there trucks so they do not move around while driving. The back towards the tail gate i was going to use a tie down to the D ring on the base of the bed. But how have some of you secured the front and sides?

Thanks for any help or suggestions.

 

I figured it out. For the front part I bought a eyelet bolt and it fit perfectly through the little drain hole. Seems to work well. And used rope to secure the platform.