Would it be completely unreasonable to allow `fundrawtransaction` to use unsafe outputs?

I understand this means the resulting transaction may be invalidated whenever the unsafe output I'm relying one disappears (e.g. because the transaction that produced it was RBF-ed) but in my case that's ok, I'll react to that and re-publish the tree of child transactions accordingly.

But let me know if you think that's too much of a footgun for users, in that case I'll architect my solution differently.
{
    CMutableTransaction txNew(tx);
    if (!->DummySignTx(txNew, txouts, use_max_sig)) {
        return std::make_pair(-1, -1);
    }
    CTransaction ctx(txNew);
    int64_t vsize = GetVirtualTransactionSize(ctx);
    int64_t weight = GetTransactionWeight(ctx);
    return std::make_pair(vsize, weight);
}
int CalculateMaximumSignedInputSize(const CTxOut& txout, const CWallet* , bool use_max_sig)
{
    CMutableTransaction txn;
    txn.vin.push_back(CTxIn(COutPoint()));
    if (!->DummySignInput(txn.vin[0], txout, use_max_sig)) {
        return -1;
    }
    return GetVirtualTransactionInputSize(txn.vin[0]);
}
void CWalletTx::GetAmounts(std::list<COutputEntry>& listReceived,