Ok, so finally, if I understand correctly,
1. You get the Antenna (NMO150 in this case which has NMO compatibility)
Right. NMO's are standard. In the Larsen product line, the NMO mounts will work with the NMO-prefix antennas. Different brand antennas that are NMO will work with other mounts. That'll give you a lot of flexibility if your needs change down the road.
2. Measure, gauge, etc, do the setup properly
Use 2" wide masking tape. Put down a strip a couple of widths wide and a foot or so long. That gives you a good working area. Make marks where you want to drill. Make sure you know what is on the other side. Don't drill through stiffening braces.
3. Drill the hole (center of trunk, make sure to note where it touches window when lifted and adjust)
A note on hole saws...
There are NMO hole saws that are specifically designed for installing these mounts. They are pricy, but they do a nice job. If you plan on doing this frequently, they are worth the investment. They have a design that limits the depth so you don't accidentally drill through a headliner.
There are also perfectly acceptable 3/4" hole saws sold at hardware stores that will do what you need for a lot less money. They don't have the depth limiting design, so you need to be careful. But since this is going on a trunk lid, you don't need to worry about that.
Expensive NMO hole saw that does a great job:
3/4" Hole Saw. X-ACT hole saw cuts a 3/4" hole x Depth 1/8"
theantennafarm.com
Or, head over to Home Depot and buy this:
Designed with a robust 1/4 in. quick change hex shank, Milwaukee Shockwave Impact Duty Thin Wall Hole Saws give professionals a hole making solution to use with impact drivers. Utilizing a thin wall, 8 TPI design, Thin Wall Hole Saws deliver a burr-free cut up to 40% faster than standard...
www.homedepot.com
Those will work fine, I've used that exact one in a pinch.
Go slow when you drill. Use light downward pressure on the drill and let the hole saw teeth do the work. You don't want to use too much pressure and build up heat.
4. Use one of
these (or any) NMO mounts (Male BNC in this case)
[linked this one because it's the one I found that I think I'd like to get if I understand it correctly], install that NMO mount through the hole
You don't need the HF style mount for what you are doing, but it certainly won't hurt, and it's only a few bucks more. You can get the NMOK mounts with the BNC connector on the end for a few bucks less.
But, before you install that, make sure you carefully clean up all the drilling chips. Vacuum those up, use a magnet, wash the car, just make sure you get them all cleaned up.
When you install the mount, make sure the O-ring gets installed correctly. Some mount kits come with a little tube of silicone grease that helps keep the O-ring in place, and help keep it slippery so it doesn't bunch up and get damaged when you tighten the mount.
The instructions will cover all that.
You'll need a small pair of needle nose pliers to hold the center section as you tighten the outer ring. You can buy fancy wrenches, but a small set of needle nose pliers works just fine. A large adjustable wrench will work fine on the outer ring if you don't have a open end wrench large enough. Tighten it down snug, but don't make it so tight that it deforms the metal. You can always tighten it later.
5. Affix the antenna to just-installed mount
The antenna base will have a space for an O-ring or a separate gasket. Use the gasket that comes with the Larsen antennas, it'll keep moisture out and protect the surface of the trunk.
6. Wire the cable through the car
Careful routing is key. Avoid sharp edges, and try not to run under the carpet in a place where it'll get stepped on.
Keep it low to avoid side curtain air bags. Try to avoid other vehicle wiring if you can.
7. Connect it to the radio and good to go
Yep, that's the fun part. I suspect you'll notice an improvement in performance right away.
Periodically remove the antenna and clean under it. The gaskets work well, but keeping the mount clean and making sure a bit of moisture didn't get in is important. A bit of preventative maintenance goes a long way. I've got 30+ year old Larsen antennas that still work just like new.
Hopefully I understood that right. If so, I believe all I need to do left is touch up/learn actual procedures/tape usage/measuring/drilling/etc. I could get it done for me I suppose, but I think it would be good to still have knowledge of it at least.
It's not hard. Just take your time. Measure twice cut once (rather than the "I cut it 3 times and it's STILL too short….)
Beware of Youtube when it comes to NMO mount installs. There are a lot of truly horrible videos on their that give really bad advice. Avoid the videos from ham radio operators if it seems fishy. Try to find videos direct from the manufacturers.
Photos when you are all done are much appreciated, as it helps others down the road to see how it's done. It also reinforces the idea that permanent installations are a good option.