It's actually not a tough job at all, granted you have a few things:
1) a bit of mechanical / electrical skill
2) a "brake ready" axle (look at the axle end with the wheel taken off - if it has a square flange on the end with 4 bolt holes - it's "brake ready" - most are).
3) a "brake ready" trailer tounge (if your current coupler is bolted on, not welded)
4) tools - wrenches, ratchets, drill + bits, screwdrivers, rubber mallet
The tounge can be relatively easy, granted that yours is not welded on. Remove the large bolts holding it on and with a rubber mallet, pop it upwards from the bottom. It will pop right off. The new coupler/actuator is a "all in one" unit that bolts on, using (hopefully) the same bolt holes as the previous one. That was the hardest part on mine - the old, non-actuator coupler that I removed did not have perfect factory bolt holes to allow the new actuator coupler to use the same holes - therefore, drilling had to be done.... and WHOA BOY... that steel is STRONG. I ruined a good carbide drill bit doing mine. Hopefully, you won't have that problem.
Next, connect the backing solenoid to the rear of the actuator coupler. Then connect your main brake line to the back of the solenoid and run along the trailers channel to the rear axle and connect to the distribution valve. Attach the distribution valve to the trailer channel so that it is solidly mounted.
Then, take your tires off on the axle you are mounting the brakes on. Remove the old hubs. With the old hubs completely removed, you have plenty of room to mount the caliper brakets. Attach them each with the 4 bolts. After the brakets are on, put the new hubs / rotors in place. Then mount the calipers, sliding the brake pads on each side of the rotor. (Note - on some kits, the caliper mounting plate / calipers have to be mounted after the hubs are on - depends on which kit you get).
Then route the brake lines from the calipers to the axle and secure temporarily with wire ties. Mount the hard lines to them and to the T-coupling, and then mount the flex line to the remaining opening in the T-coupling. Mount the other end of the flex line to the distribution valve you previously mounted (attached to the main line you previously ran).
Now that all the "plumbing" is done - you need to connect another wire - the backing solenoid actuation wire. On most of them, the wire is blue. You can either cut off your old 4 wire flat connector and connect a five wire flat in it's place, connecting the new blue wire to the new "extra" wire you will see on the five wire connector, and then putting a five wire connector on your vehicle, connecting that new "extra" wire to your back up lights (when your back-up lights come on, it locks-out your solenoid when you put your truck in reverse so your brakes don't lock as you are backing up). Or... if you already have a 5 pin, or 7 pin on your truck side, you can just put the new 5 wire on the boat trailer and use an adapter. Really easy to do actually.
Then, pop the actuator cap and fill it with brake fluid. If you don't have someone with you, use a "one-man brake bleeder" kit, available at auto zone. Bleed the caliper that is furthest from the actuator first - usually the one on the port side of the boat. Watch the fluid level as you are bleeding to ensure you don't get air in the system. The easiest thing I've found to do is get a 2x4 and put it in front of the actuator with one end of the 2x4 on the ground. Put your foot behind the part on the ground to keep it from moving as you push the actuator in with the top part, using the 2x4 as a lever. You will have to pull the actuator out manually, and then do it again... and again... and again - several times, until the brakes are bled - each caliper at a time.
There are several kits available. I have installed both the Tie-Down kits and the Kodiak kits. I prefered the Kodiak<
