While waiting for usage to be sufficiently high to get security by transaction fees, it is easy to introduce a PoW component (which also solves the initial distribution problem).

Rather than completely destroying half of all transaction fees, they would instead be set aside to be claimed by future PoW transactions. PoW transactions would be added to the TDAG much like any other transaction, but would contain a PoW instead of inputs. Additionally, PoW transactions would be restricted to only descend from TDAG-nodes with unclaimed transaction fees from the "burnt" half, to ensure that miners have an incentive to include recent transactions.