Hello!
I am wondering if this is a good idea.
Luckily, the authorities in my part of the world have decided for me, regarding this question: Descending below 500ft for practice forced landings is only permitted during flight training for licensing purposes and only with an instructor on board. But our students have to practise (and demonstrate) forced landings solo from 2000 ft above an aerodrome.
As for spins, those have been removed from flight training (dual and solo) long before my time. And that was really long ago, because I'm not so young anymore. So probably they can only be practised solo because there are no instructors around who are current in spins
Greetings, Max