I've played with chastikey, but it really just depends on trust like anything else.
I've looked into the devices that are remote controllable, and there's been a lot of talk about remote hacking and having to have them cut off to get out.
I've been locked for weeks with a remote keyholder with nothing more than the keys in a paper envelope taped and dated.
If the keyholder can't trust the sub, then what's the point?
For self-chastity, getting one of the little home "lockers" can be good too, and they could also be used for remote play, set the timer on them for the max, and the keyholder checks in before the time is up, and gets the sub to reset it for the max again.
Something like this
Why on earth is that pathetic... I can't even call it a cock, not already locked up?
Get rid of all that nasty-ass hair and get it into the smallest cage you can find: this will do for a start.
I'm actually a cuck in 24/7 chastity, but you clearly need my help (imagine needing help from a cuck lol). I thought my dick was small. Message me.
They sell it all over the place but here it is at Amazon where I got it. New The Biosourced Resin Male Standard Chastity Devices Male Briefs,with 4 Size Rings T-Shirt Red https://www.amazon.com/dp/B07PLVFJHD/ref=cm_sw_r_cp_apa_i_z1pcDbBGSVZ9M. It takes a doctor's degree to get it on the first couple times but I love the thing other than I can't where are my yoga pants without looking like I'm packing a massive cock. It is a little difficult to hide under tight clothing
These numbered plastic locks @Amazon are simple, cheap and kindof -effective.
This Realator'sLockBox @HomeDepot is good to hold keys. You can provide the combo as needed.
RE: night erections. They do go away after some time. But near term, the best solution is for him to get up and empty his bladder immediately.
IMHO: if he's cheating the lock already, it sounds like he needs or wants discipline more than he wants chastity. Perhaps a topic for discussion