I have huge problems with MET's card draw system or the rock paper scissors system used by other vampire LARPs. Both systems heavily favour more powerful characters making it difficult for new players to join up, further they are not intiutive further they require character sheets which slows the action down. Now if you want to encourage your players not to use the mechanics provided and you don't have a handy place to hold dice then those systems will do.
The only LARP without live combat I've experienced work is called Shelter in place. It is ideal for games with few players in enclosed spaces, though it helps if you can move the furniture around a bit. I don't know how well it will adapt to high fantasy (it is designed for Horror LARPs), nor how it'll stand up being run as an ongoing LARP. But it's a neat little system for a oneshot, it is easy to learn to play and simple to run (your monsters generally have one or two stats while your Players have two stats, a special power, and a special power that activates when a mini objective is completed, all unique- these can be printed on cards for reference without slowing the game down), does not require many props (aside from the above mentioned furniture and a few everyday bits and bobs, like boxes of candy) or much space.
If you aren't married to the idea of a high fantasy LARP I suggest this, you'll be able to go from buying the books to running your first session in a matter of days if you run it as written, most LARPs take months to set up. Also, it's cheap as chips.
Here's a link:http://www.indiepressrevolution.com/xcart/product.php?productid=17988
Why are you LARPing rather than playing pen and paper games? With your avaliable playing area and numbers it seems to me that SATT is the more viable option.