Running the alternator feed to the hot side of the starter would work, if the battery was mounted in the stock location. It would need a fusible link or an in-line fuse for safety too. That's really not the way it should be done for your application.
It's ok to put the battery in the trunk (if you do it correctly), but it's not cool to have constant power tied into the main starter feed cable. If the cable ever got cut (or tied up in the drive shaft) and it shorted to ground, there'd be no way to keep it from toasting its self.

Here's how I did my friend's track car:
The battery is mounted in a battery safe, which is bolted to the floor. The battery is bolted down with a hold-down and the lid is secured as well.
There's a tractor supply store just down the street, so I got the biggest cable available ((2-0) double ought). I used brass eyes so everything could be soldered together and wrapped in heat-shrink tubing. I ran the ground cable to a bolt on the back of the trany tail housing, that way the engine gets 100% ground.
I ran the + cable to a rear mounted master switch. From the m.switch it feeds to a Ford style remote starter solenoid, and from there it feeds the main cable up to the starter. I made a junper wire to connect the main battery lug on the starter over to the "start" lug.

From the "feed" side of the remote starter solenoid, I ran a fused (50amp maxi) main power wire up to the fuse box. I then ran a 2nd circut using a 100amp maxi fuse for an alternator feed. The 3rd circut that I had come up with was a start circut to energize the solenoid for cranking.
With the master switch in the off position, everything is dead. Makes for a good theft deturrent too. With it turned on, all accessories have power. The only time the main cable to the starter has juice, is during cranking.
It's not an easy task to do it properly, it is by far the best way to do it. If you make it look good, people will think it's a cool deal as well.



Good luck.