omg this is hard, I tested playing under these conditions last night after posting this. I had about 150 horse wagons and payed back my loan by 1856. I had trouble finding 2 towns that was easy/cheap to connect by train. the only 2 that was easy to connect was under 100 in population. I will play more and see how it goes later this evening hopefully.
How has the challenge been for you? have anyone tried yet?