Since you mentioned you already have a Yakima rack, you may wish to have longer bars than the stock Isuzu 34" bars.

There are guys who found towers that fit our VX and hold round bars, but I think the best option is to use the custom Yakima towers for the VX (available through Isuzu) with 48 or 58" Yakima wing bars.

With inexpensive Wing Bar clips (available from Isuzu and *some* Yakima dealers) you should be able to use most of the racks you currently have on your old Yakima rack. Wing bar clips are basically just odd-shaped Q clips.

Rack Warehouse may be able to sell you Wing bars:
http://store.yahoo.com/rack-warehouse/y0309c.html

They hooked me up with a set of 58", but they really want to sell the bars with leftover towers. That 48/58" bar set with towers for only $84 is most likely cheaper than the 34" bars alone from Isuzu, and you can toss the towers and cut the bars down to any length you like with a hacksaw.

I may consider selling my used 48" Wing Bars also.

Good Luck,
-Daver