Having a little clearance is preferred since it allows you to align the wing, engine and tail. You can take up any errors that may have crept in elsewhere, like the engine bearers after they were epoxied in. So 1/16" all around sounds about perfect.
Something people can be bit by, is that a really tight fit--which sounds good at first--puts strain energy into a clamp-up for gluing. So when you take the assembly off the bench, you find out it is crooked. Alignment is the number one issue. The joint is fine when anchored with epoxy-coated balsa shims. Sand the shims until they are thin enough that you do not have to force them in.
I guess I should say that my preferred method of gluing up this joint is to clean off the bench. clamp the nose of the fuse to an angle that will hold it 90 degrees to the bench surface, but lets you tilt the tail up and down. Tilt until you get the engine mount parallel to the bench. Put a wedge block under the tail to stabilize it there. Measure carefully. Slide the wing into the slot. Double check the fuse alignment. Put equal shim blocks under each wingtip to get the wing parallel to the bench and square to the fuse. Use a drafting square or the like to get the wing square in the top view. Measure both sides to make sure the wing has equal (or the intended offset) panel lengths. Finally, measure the center of the LE and center of the TE height above the bench. Get these absolutely equal if you can. Some people like to use a Robart incidence meter. If you have one, Great! Insert epoxy coated shims at front and back. Use 30 minute epoxy, not anything quicker. Check all of the alignments again. Let it set up. This is like tack-gluing. If you are happy with the alignment, then sand, trim and epoxy coat the rest of the shims and insert. Once it is tacked well, you should be able to take it off the bench to fill in the rest of the spots. Don't force fit anything.
You should not need any weights to hold the parts down or try to hold something straight. If you do use weights this way, the structure will spring back when you take them off and it will be misaligned.
The same applies to installing the tail. Get the alignment straight on the bench. Use equal height blocks. Fake credit cards work good for shims. They come in a wide variety of thicknesses, and are free for the opening of your junk mail. Use the ones without the embossed numbers. If the wood is in contact, great! If you have to add weights or in any way force it, take off some material on the fuselage to get it both straight and free. Then epoxy. The epoxy is stronger than the wood, so don't worry about filling a gap. Don't fill huge gaps with epoxy because it is heavier.
Sometimes a bit of masking tape is helpful to control where the epoxy goes. Usually not needed.
I used to glue and fill a wing joint at the same time using SIG's Epoxolite. I wouldn't try it with the blue Super Fil. It doesn't seem to have the right properties. So fill with balsa where you can, because filling with epoxy is heavier. Be sure you get a solid balsa shim right over (and under) each wing spar, and at the LE and TE.
Good luck with your Akromaster. It should be fun.
Dave