Aloha Old Fred,
I've had great success with the FOBO TPMS system when I had a 2016 GL1800 and this will work with any 2017 and older bike.
It has an app which links it to your smart phone, you can set your pressure limits and will set off an alarm through your smart phone if limits are surpassed.
I also like that you can check you tire pressures on your smart phone without having to crawl on the ground.
But remember, you still need to visually check tires for road debris damage.
It's also best to use a "T" valve so you can add air and not have to reset sending units.
The sending units also have replaceable batteries that are available anywhere and they're cheap.
One last thing, call CSC Trikes and order a plug and play wiring bypass for the stock TPMS warning light on dash which is around $50, if the light staying on bothers you.
Hope this helps you as an option.