I say go for it.
It's (probably) not illegal. If the resort is encouraging guests to use the Wilderness nude, then I expect they've checked the legalities of the situation. If it is legal to be nude there, the best thing people can do to normalize nudity is to BE nude there. Why should free hiking be limited to people who have paid to use the resort? Clothing optional beaches aren't attached to any resort - usually.
If the area is truly public land and not owned by the resort (or some other entity), there is absolutely no reason not to make use of what you have been blessed with. The only caveat I would throw in is to not succumb to the urge to make use of the resorts facilities without their permission and paying the appropriate fee(s). They are a business.
John aka cobeachbum
As an update I did end up going hiking in the area and simply avoided getting into the territory which seemed very near to the resort. It was a pretty challenging hike, I look forward to possibly doing it again in the future.
From the description, sounds like DeAnza Springs Resort in Jacumba, about 45 east of San Diego. Great naked hiking opportunities. We've been there a few times. I like the entire place, my wife likes the hiking but not so much the resort itself ... too rustic for her. But the OP states he's from Pomona. He might be talking about Olive Dell Nudist Ranch in the hills above Colton. Some great hiking trails there as well.
We are members of GE and the hiking there is really limited. There is one main trail and two smaller trails but they all are within the property of GE. GE is surrounded by residents and they are encroaching on GE's property line. GE management has voiced concerns that the main hiking trail might have to be closed because the textile residents are beginning to mildly complain. I don't think what the OP is speaking of is GE. There aren't the types of trails the OP is describing at GE. It is a toss up as to which club is closest to Pomona ... GE or the once Tree House/ Deer Park club that is now called Freedom Acres. I've visited Deer Park years ago, several times but don't remember any hiking trails. Too bad the OP won't respond to the questions we all have.
To settle this debate that seems to have broken out I will say that the resort in question is in fact Olive dell ranch. The hiking trails were pretty good although many were quite overgrown. The reason I was hesitant to respond is because I know olive dell runs a tight ship and I was nervous that people would be offended that I used the trails in the hills behind them without their permission. Also thanks for these suggestions on other hiking areas etc, that palm springs group sounds interesting. Also Also I have been to deep creek as well and have to say that its great.
If you are not entering the property of the resort then there is no question. It sounds like public lands you are hiking on. If you want to enter the resort lands then by all means get permission, I bet they have student rates. Have a good hike.