just completed something semi similar
https://bitcointalk.org/index.php?topic=283817.0involving stocks not ltc.
for something like ltc i would feel safe holding 125% worth of ltc compared to the btc value which would give you the option in case of ltc value drop to either increase the amount of ltc or decrease the amount of btc loaned (by either sending some btc back or having some of the ltc get sold...your choice)
would do it for say .1btc / week
we'd have to iron out any details a bit later
just a quick reply i'm headed out to work (till 3 / eastern US) i'll check in throughout the day when possible