I'd prefer some "official" solution as I'd like to support the network with the fees (also not risking messing up user's transactions) and in the same time give our users ability to predict fees in advance before sending. Do you think its currently possible with main dist of bitcoind?
No, unless you take complete control over input selection and transaction creation using the raw transactions API.
If you have multiple users sharing the same wallet, then reasonable ways of handling transaction fees are:
Keep track of who owns which inputs and use the raw transactions API to charge users fees based on what the inputs look like.
Just pay transaction fees for your users. If you work out how much that will cost you versus how much time you'll spend with a more complicated solution, you'll probably find this is the best solution. If you're using the 'accounts' feature, then the logic is: Send the transaction, then get the transaction details and reimburse the transaction fee (if any) with a 'move' that transfers bitcoins from a transaction-fee-reimbursement account (which you finance in advance, and top-up when necessary) to the user's account.
Or charge them a fixed fee that is enough to cover average costs (again, if using accounts you'd move bitcoins to/from the transaction fee account depending on whether a given transaction cost more or less than average).
Otherwise, you'll have a situation where user A gets gazillions of tiny inputs credited to their account, and user B ends up paying to spend them.