I would suggest a different approach to mining. If it takes a specific time for mining fields to regenerate, they will just never regenerate as people will simply keep mining them, even while the field is low. I suppose this is determined by the willingness to mine for long periods of time. However, there is always someone willing to do it.
My suggestion would be to either have the fields regenerate at specific intervals throughout a day or perhaps even have them at random intervals. That should be fun. Therefore if a field starts with say 100000 or so ore. When it gets mined out, it remains at the low drop rate for three to four hours and then it is back up to the original 100000, no matter who continued to mine it. Thus always allowing for someone to determine when they would like to mine. It would also be interesting to even divide the fields up themselves. Starting from the center and moving outwards. Say 5 kms, then 10 kms and so on. Forcing miners to move away from stations the more they mine. It also allows players to spread out and increases the chances of piracy.
For the smaller mining ships I would suggest a more long-term approach. Make them freighters instead, with a 500 cargo capacity and with the ability to either drop the cargo at a press of a button or alternatively, if there is a hegemon or transport handy, a means to beaming the cargo there instead of to the freighter.
My last suggestion would be to increase the number of fields, make mining interesting by allowing miners to move all over Sirius. Also, increase the number of selling points, have one in each house. Determine the price via the length of time it takes to get there from the mining fields. Thus miners can also choose whether they want more profit and more risk or less profit and more time to mine.
So far I like what I see, there may be kinks that need to be ironed out, like having nothing to mine yesterday. However, the outcome should be incredibly exciting with a major impact to how RP is done. Thank you for trying to solve this mess. It is appreciated.