RCI, season is more important than room size, so if you want to deposit some with better trading power, deposit 70k, 105k.
Being that area has very very few resorts, and being that resort is highly demanded in WM, and being that Wyndham has no perference for WM in RCI exchange, I will assume it is very unlike you can get it through RCI week exchange no matter how many points you deposit. That resort is not in RCI point resort. So you will not get 4 days through RCI exchange.
That resort does has exchange program with Wyndham, usually, it has 2 or less unit, in this case, I will assume it is 1 unit. You will need probably 150k for 4 nights. You will have to hope they keep the relationship.
At this moment, you have nothing you can do, if they do continue the relation, you can try to check when they get into the system by calling at exact 10 month before your check in day, except it is for 2009, than going backward until the VC find the 1st unit available, than you will assume it maybe the max day you need to call in, so say, if you call today, the 1st unit the VC saw is 7/10/09, it is very likely they deposit to system at 9 month, than you call next time and try to confirm it, so you call at 1/1/09 to see if you can get 9/1/09, and maybe 10/1/09. Try it few times until you think you know the deposit time. They could deposit it in batch, say each time they deposit it as 2 month inventory, if that is the case, you should be able to figure out when is the min batch day, and when is the max batch day, and figure out when is the 1st day the inventory will be in the system.
Than they usually have the contract year to year, so you need to figure out when they start a new cointract, and when the old contract end.
I believe the last time I saw it is at April, so you probably can assume the batch is from April to March. And try maybe 9 month or 10 month period.
Also, try exchange with WM owner, or rent out your point and use cash to rent 4 nights in the park's cabin. It is much easier, more flexible, and you may get better accomoldation if you are looking at shoulder season.
Jya-Ning