### FEATURE REQUEST

Currently, when a bitcoin node is set up with a connection to both TOR and normal IPv4/6 internet, the 8 outbound-only connection slots, almost always get filled with nodes connecting over IP.
Adding a config option, which would try to ballance these connections based on what kind of network they go through, would be benefficial in many ways:

1. It would add edges between bitcoin network on TOR and normal internet, reducing delays, and the risks associated with an attacker isolating a part of TOR-bitcoin-network from the rest of the world
(Or an ISP/government man-in-the-middling all the normal IP connections)

2. It would help hide/annonymise normal user's transactions from his/her ISP, by mixing them with TOR-outbound ones

3. It would reduce the stress on normal general purpose TOR exit nodes, as users would more likely/reliably connect to TOR-IPv4/6 bitcoin nodes instead of exiting into normal internet first, and then connecting to default IPv4/6-only bitcoin nodes

I understand it is possible to create such bridges already, by forcing connections to TOR-only nodes, or by just running a node with lots of inbound slots, but I think the proposed option, would greatly increase the number of such relays, and remove the need for user to maintain a TOR-node whitelist, by handing this work off to normal bitcoind connection finding algorithm.

This could be implemented as a minimum number of connections for each network, or just a simple evening boolean switch. (Which could be enabled by default for bitcoind installs with TOR connectivity)

In the future, if bitcoin was to support a new network type (for example cjdns/I2P/GNUnet), this option would help establish a presence on the new network faster

bitcoind: 0.15
if (hdr.nMessageSize > MAX_SIZE || hdr.nMessageSize > MAX_PROTOCOL_MESSAGE_LENGTH) {
        LogPrint(BCLog::NET, "HEADER ERROR - SIZE (%s, %u bytes), peer=%d\n", hdr.GetCommand(), hdr.nMessageSize, m_node_id);
        return -1;
    }
    
    in_data = true;
    return nCopy;
}
int V1TransportDeserializer::readData(Span<const uint8_t> msg_bytes)
{
    unsigned int nRemaining = hdr.nMessageSize - nDataPos;
    unsigned int nCopy = std::min<unsigned int>(nRemaining, msg_bytes.size());
    if (vRecv.size() < nDataPos + nCopy) {
        
        vRecv.resize(std::min(hdr.nMessageSize, nDataPos + nCopy + 256 * 1024));
    }
    hasher.Write(msg_bytes.first(nCopy));
    memcpy(&vRecv[nDataPos], msg_bytes.data(), nCopy);
    nDataPos += nCopy;
    return nCopy;
}
const uint256& V1TransportDeserializer::GetMessageHash() const
{
    assert(Complete());
    if (data_hash.IsNull())
        hasher.Finalize(data_hash);
    return data_hash;
}
std::optional<CNetMessage> V1TransportDeserializer::GetMessage(const std::chrono::microseconds time, uint32_t& out_err_raw_size)