I recently installed a V1 and Zumo on my '08 GT (both on mirror mounts, both fed from a Cenotech AP-1 fuse block), and am adding a Cheetah / M25 laser jammer this week so this stuff is pretty fresh in my mind. I'll also be adding an Autocom and then I am DONE with the farkling! No really!
A jammer is almost entirely out of sight but yes kind of spendy. The Cheetah control unit sits under the seat and the only visual indicator is a very small LED block that can go on the shelf or in your helmet. Hoping it will buy me a few seconds to notch my speed down before flipping it off, but as noted laser jammers are still pretty new and there isn't much anecdotal evidence yet. The State Patrol around here all have lasers and love to use 'em, so it prolly won't be long before I get a feel for whether the M25 is working for me.
A fuse block is pretty easy to install. Cenotech makes some nice ones, and so does Blue Sea Marine. Waterproofing and/or marine-grade components are a Good Thing.
Most fuse blocks are pretty small, and can be hidden in any of a number of locations. On top of the battery, secured by velcro is a popular location on the GT. Under the seat is another good location. Both are mostly out of the weather.
Whether directly wired or going through a relay, a fusible link or inline fuse is required to keep the battery from catching fire in the event that the fuse block has a problem.
If the fuse block is wired directly to the battery it will be always powered on. If you add a relay in between the battery and the fuse block, and connect the relay's coil wire to a switched circuit like the parking / running lights then the fuse block will only be powered up when the key is on. Might sound a little intimidating but it's really no big deal. There are little clamp-on connectors that make it very easy to tap into an existing circuit for this 'trigger' functionality. My fuse block is currently hard-wired but but I'll be adding a relay when the jammer goes in. I'll try to remember to take some pics when I do it.
Any car stereo installation shop should be able to give you good advice on fuse block installation if you need some face-to-face help, and of course there is a bunch of wisdom available on this site.
Once the fuse block is installed, you have a bunch of easily accessible connections available to power the rest of the farkles. Connecting to the power terminals is a snap, but routing the wires requires some attention to detail so that at no point can the wire be pinched by the forks during a turn, etc. The wires should be attached to the frame or other non-moving components with cable ties every few inches to keep them from flopping around and getting into trouble, chafing from vibration, that kind of thing.