I'm no top notch flyer, but after talking to some of my local good guys I use the following system, or variations of.

I use a 'jesus' bolt through the bellcrank pivot. The bellcrank is mounted as per a standard floating bellcrank, on tubing that is a snug fit to my jesus bolt.
That's mounting point one. This bolt is usually a long M3 (4/40).

I either use a flat (horizontal) tongue on the front of the wing (1/8 ply) and secure it to a suitable flat plate area on the front fuselage. An alternative is to brace a vertical piece of plywood against the LE and bolt it to to the rear tank bay bulkhead. Either way these bolts can be secreted easily under the cowling.

At the TE I extend a U shaped horizontal piece of ply past the TE of the wing (with a suitable cutout for the flap horn) and mate this against a ply plate mounted in the rear fuselage. Extending the wing plate past the TE makes it a little easier to get at the controls for disassembly/fine tuning.

It doesn't seem to matter much (on my models or level of flying) whether I use 1 or 2 bolts at the front and rear.

Its important not to over tighten any of the mounting screws when assembling the unit, and if you don't disassemble the model often just check the mounting bolts regularly. The only time I noticed any of my bolts come loose was after I clipped the prop on takeoff, and that was just a single bolt that was affected - the jesus bolt remained tight, as did the bolts at the rear of the wing, so I have a high degree of confidence in this system.

It has also survived the required pull tests on a regular basis.

This system has been around for a long time (70s?) and is relatively easy to assemble  for the average builder.

I acquired a model from a fellow flyer which used a similar system but with plastic bolts holding the rear of the wing in place. This was a 60 powered model and had participated in the world champs - it still had the pull test sticker to prove it. Don't over-engineer your solution.

A neat trick I've also adopted is to make the cowling long, so that the cowling extends far enough back to cover all the necessary screws.
I also like to use allen head bolts wherever possible as the tools associated with this type of bolt appear to do less damage to my models.

I've found that re-inforcing the fusleage with glass cloth (internally) back to the TE mounts is more than adequate.