I understand that you say "no holes can be drilled" but that is the absolute BEST ground you can achieve in a mobile setup.
You have several mounting options on a truck. Can you do any metal fabrication/are you good with a soldering iron and crimp tool?
One trick I've seen is buying an NMO connector(under $25 on amazon) (the kind you need to drill for) and fastening 2 pieces of metal - essentially sandwiching them in the truck bed tie-down openings using the NMO connector as the bolt and nut. The ground is less than desirable but it's still a very functional mount system.
Another trick is to buy a backrack and mount antennas to that. Alot of the redneck bretheren with deeper pockets use the dual CB antennas you'll find on semi-trucks mounted to those. But you'll have the same luck with mounting a broadband antenna on it also.
Lip mounts (from personal experience) tend to rust out over time even if they claim they don't and cause havoc on your paint job.
Bottom line is, if you're serious about the hobby and the truck is paid for, drill, drill, drill. I mounted 2 NMO's on my Chevy Blazer in 2006 and they don't leak or rust. Odd part is, the rest of the vehicle is rusting, but not those!
Once you can get the coaxial line in the cab, it's a matter of slapping a BNC or PL-259 with an adaptor on the cable and you're in business.
Also, if you ever go to sell the truck, you can just install this:
http://www.theantennafarm.com/catalog/antenna-accessories-481/rain-caps-hole-plugs-1026/ or a similar product.
