Temazepam to Mirtazepin?

I am reading the posts here on this subject but in the interest of speed I am asking a question before I finish:

74yo man with a variety of health issues and limited access to quality care.
Before I go into any more complex details, the basics.

I have usually been able to keep depression and anxiety at bay without meds or therapy, except during triggers life events, for which Temazepam has been
effective (15mg 2-3 days, few times/year).

A recent trigger has induced insomnia. Even though I have decent sleep hygiene, I walk briskly 1hr/day and do not sleep/nap during the day, for the last two weeks am unable to fall asleep without at least 7.5mg Temazepam daily and that gives me
only 3-5 hours of sleep.

My GP recommends the tetracyclical Mirtazepin for its dual action on both depression and sleep, I researched it and:
* don't like what I read about it;
* I took a tricyclical decades ago and hated it
* withdrawal and rebound.

I researched all AD and sedative options available and found none attractive, to put it mildly.

I realize it's no substitute for medical advice, but it may take time to get access to a good specialist -- if at all -- so I would appreciate any help/comments.

* How long can I expect daily Temazepam 7.5mg to be effective and safe?
* Is Mirtazepin the least bad option?

Thanx.