Helibars I've had a Helibar Gen III riser on my ST early on and highly recommend it if you feel wrist/shoulder/neck pain from leaning forward on the bars. It made a huge difference for me making the bike far more comfortable. I have a DIN/powerlet port and a RAM ball where I mount my phone for GPS.so I'm starting to shop for farkles!
GPS A personal choice. I don't ride enough to justify a dedicated GPS except maybe the Chinavision that Uncle Phil uses. I use my phone in the powered Helibar and a RAM X-Grip or Hondo Garage mount. I use Apple Maps for around town stuff and Navigon (nav app) for offline use. Using a phone for GPS is sacrilege and inconceivable for some riders but it works for me. It's powered by adapters from the DIN socket as GPS will suck a phone's battery dry in short order. I don't ride in the rain so a ZipLock bag over the phone works for me.
MCL Unfortunately I'd echo the warning of avoiding MotorCycle Larry at this juncture. Communication is one sided and it seems currently standing orders are going unfilled. While it could change I have no hope of MCL becoming once again a reliable source for parts.
Tip Over Bars I'm going the GoldWing bar mount route without the adapter plates. I do light the idea of bushings in the frame recesses as standoffs to keep the bar 'feet' off of the frame. Not really necessary but I still like the idea. I don't carry a passenger so fitment isn't an issue in that respect.
Auxiliary Lighting Front BIG fan of it but haven't as yet added any to the front. The plan is two large (4-5") lights mounted under the mirrors. I did install Evitek G6s in the headlights and highly recommend them as well has checking the alignment after installation. I've also got switchback LEDs and clear lenses for the turn signals. Some people seem to have no regard for how their lights affect oncoming traffic. As a responsible rider light choice and use are important as you're not always the only one on the road.
Auxiliary Lighting Rear BIG fan of that too. I've got an EMS flasher replacing the reflector and connected to the brake light. Mine flashes four times then pauses and repeats while brakes are applied. I notice many cars slow quickly behind me instead of approaching quickly and stopping at what seems like the last minute. Some stop a couple of lengths or more behind me. I've replaces my turn signals and brake lights with LEDs that are brighter but don't like the lenses quite as evenly. But they are better than the factory lights especially the anemic taillights. The turn signal bulbs are switchbacks also (amber/red) and will get the extended brake light modification in which they also act as brake lights unless you use a turn signal. I also have a steady LED brake light mounted in the pad of the bike rack. This will probably get a mod too. I'm deliberately avoiding a visual cacophony of flashing light as I think it's counter productive.
Any mods but especially lighting mods should be done after knowing the lighting laws of your state and assessing your willingness to violate them.
Maps/Tank Bags I don't use them and have no opinion.
Cruise Control I also use the Go-Cruise throttle lock. Nicely made very functional. I'm thinking of replacing it with a Vista-Cruise throttle lock because of the more integral mounting. I've taken two long trips of several hours a day and find a throttle lock sufficient. For me a cruise control would be a convenience/extravagance where others find it a necessity. Your call.
As far as installing any farkle I'd start with the cheapest easiest first and work your way up since you have time. I'd give priority (if needed) to headlight LEDs and auxiliary tail and brake lights. Converting to all LED lighting lightens the electrical load on an already marginal battery. (A battery tender is a good idea during hibernation.)
Two additional inexpensive relatively easy farkles are the parking brake and voltmeter mods. The parking brake is very handy and used it a lot more than I ever thought likely. A voltmeter of some kind is a good idea again because the ST1300's battery is lacks appropriate capacity. There are many options for a voltmeter.
I mention the last two because they're easily done during down time and very cheap as many farkles go and have potentially high bang for the buck. No seat time required.