If and instructor can't be found, I'd say a sim and resources like RCU is the next best thing. But I think most of the experienced members here agree that there is no substitute for an instructor.

Case in Pont: I'm helping to train a new member. This evening we flew again. The student has about 30 flights under his belt since he started three weeks ago. We never used a buddy box... just handed off the radio.

Tuned and set his engine. Has some strange issue with low end mixture. He spent over an hour working on it. I showed up and had it fixed in about 60 seconds. (Sim won't do that.)

Did some basic training, aerodynamics small talk, etc. On his 3rd flight he soloed. He now flys on his own, but if I'm at the field I'll blurt out "More Left rudder!" or whatever when I see him repeat the same mistake several times. (Sim won't do that.)

We programmed his plane in my 9ZAP so I could setup some mixes to improve the handling of the plane (Kadet 40.) I explained what and why I had the mixes setup. He loved the new handling of the plane and understands why the mixes help. (Sim won't do that.)

In just 30 flights, he can easily run his Kadet thru loops, both inside and outside, inverted flight, stall turns, rolls, 1/2 reverse cuban 8's, immilmans, etc.

Now I think he is probably better than the average student, but point is, he has learned a lot more in those 30 flights with instructors than a sim will ever teach him. He probably dosne't need and instructor; BUT, I consider him to be in the "Danger Zone." He is more than capable of flying on his own, but could easily get into trouble trying new aerobatics. For this, there is NO substitute for a spotter (i.e. instructor.)

Another Case... Myself: I've been flying for six years. I compete locally flying precision aerobatics. Last year I put on 500 flights. So far this year I've burned 5-1/2 cases of glow and about 20 gallons of pump gas. Even I still use an "instructor", i.e. older Masters level pilot to help me with my precision flight. (Sim can't watch your flight and point out errors.)

Cheers