My question is short and sweet. I own an HV30 and was hoping to invest in a long lasting power supply.

First off, do any companies offer battery packs that attach to the camera's battery port, but the actual battery can be mounted elsewhere (ideally, the battery would be much larger than the standard battery size that would fit in the batter port)?

And if not, would purchasing an 8.4 v battery with a matching input as the charging port on the camera be a viable option? Or would constantly running power through that port be a problem? Also, are there things I need to look out for when shopping for such an apparatus?

I was considering making my own power source for the HV30, but I wouldn't really have a use for it.
The stock HV30 battery is 1200mah(or 1.2ah) @ 7.4V
You could make your own battery by buying a cheap NB-2L off ebay for about $8 including shipping then take out the internals so you just have a shell that locks nicely into place on the camcorder.
Once you have this shell you could buy one of these:
Polymer Li-Ion Module: 7.4v 12.6Ah (93.24Wh, 7A rate) with PCB & Fuel guage display - PL-8570170-2S-WRFG (http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4696)
and wire it up so your NB-2L shell now just has wires leading off to your new power supply that should last about 10 times longer than the stock battery. Wire multiple batteries in parallel for even longer lasting power.

I did something similar for a cheap aiptek camcorder last summer and it worked pretty good...but having these wires running out of the camcorder was kind of a pain.

Another option is to just buy a bunch of the NB-2L batteries off ebay. I think you would need about 20 batteries to match the above setup and would end up costing the exact same or a little cheaper...but you would have to change out batteries. With the other option you could power other devices that used 7.4V or less.

I really need to quit procrastinating and do my homework.