I think the system couldn't be more fair, honestly.

Yes, of course it sucks that a large FC can bid 5+ more times than you, but keep in mind you need to have 5+ different accounts (you can't bid with your alts, the game is aware of which characters are and aren't yours) and the full price for every single bid.
So take the price of the house and multiply it by the amount of accounts in your FC that have been there for over 30 days = the amount of money you need to place as many bids as humanly possible for your FC.

In my old FC's case it was 7 accounts, which turned out to be 350M total because we were going for a 50M mansion.

You have to have all that gil at the same time and distribute the appropriate amount between everyone to bid (you should also make sure you trust these people to not run away with your gil). When you have a lot of bids you can place, it's also important to place them asap to intimidate others into choosing a different plot. That is why people will often advise you to wait until the last possible moment to bid on a house, since everyone is done with their bid dumping and you can see which house has the least competition.