Well I am wondering if it is viable to play white scars without the bikes. After some thought I realized that taking a rhino in a white scars army is rather good, but I started to think how to get more bang for my buck.
First off if you take khan have to look to see if he still gives scout without taking a bike. Anyway you can start your whole army in the middle of the board. Most people have been using bikes for this purpose, but you can use 10 marines in a rhino.
Now starting mid field already puts you within rapid firing range. If you move 6" with your transport and 6" with your guys it puts you in the players deployment zone. What this does is allow you the ability to rapid fire the hell out of your opponent turn one. Even if you go second the remaining squads can press up and rapid fire away.
The beautiful part of being whire scars is you can use hit and run to break combat and rapid fire or over watch.
They key issue here is providing cover to your vehicles and upgrading them to not break down in terrain. Rapid fire weapons would be good as well as assault weapons using this strategy.
I would take tigiris for prescience or any upgrades that helps with acurate bolter fire.
This is akin to what deep strike assault does, but you can do it with your entire army.