I had an electronic system in mind, similar to the systems I use for about ten years without the slightest problem on my Citroens.
I do not mind kneeling down to check the air on the +4 by myself, but the rear tire on the threewheeler is a different story - there is this young lad at the tire shop around the corner, who normally checks it for me two times a year.
Thank you for warning me about mechanical systems that might introduce an airleak instead of being a means for controling the pressure.