I have been in this only two and half years now and I have 4 "flyable" planes right now. (I have had 3 others.... but... you know) Anyway, all 7 planes were tail heavy to one degree or another. These were 3 kits and 4 ARF's.
I just try to use the battery and radio gear the best I can to balance. Then... I add a heavy hub,if needed, instead of a spinner. (Harry Higgly also makes a "lite and heavy" lock nut to be used in conjuction with his hubs INSTEAD of the normal washer). It is a thin nut, 3/16" thick, about 3/4" hex. The heavy lock is brass and weighs 1/2 oz.
Try moving the engine forward on the mount. Add any weight as far forward as possible
If flying from grass.... put on the largest wheels you can that don't look goofy. This is not really for weight ahead of the CG, but for helping the plane roll better in the grass.
In my opinion the .40 LA will struggle slightly to get that plane airborne .... even as a trike.
I didn't like my LA in my Hobbico SuperStar 40. I replaced it and stored it away. I built an LT-25 last winter that only weighs 4.25 lbs dry. The .40 LA found a "home" in that light plane, even with the span at 63". I built the wing with almost no dihedral, and I fly it as much as my big planes. I cant believe the vertical this thing will pull.... not unlimited... but really nice.
Don't get discouraged.... stick with the taildragger configuration. If you have a problem, stick in an OS .46 FX or .46 TT pro. I know 2 guys with this como and it is a GOOD one.

PS. A Saito .56 would be even better!!!
That's what I put in the Superstar 40..(over kill I know.. but it was destined for my new project at the time).
Ya gotta love the 4 stroke sounds!! That LT-40 would look AND SOUND cool!!!!

lownslo....... Bob