Use second context on top of db but with another store version

Hi, in my case I need to start some math every N block. Math operations started in separate thread, and after N blocks their results will be committed as hash into chain.
Right now I found a solution, but wondering about it validity. I create every N block new readonly ctx on top of default app db with version of this height, and latter use it for parallel computation. Pruning option is set to “nothing”. How valid is my solution? May be there is other better options?

Also, it will be nice to have possibility to change pruning options (and it’s params) for individual store, rather than for whole root store.