I was just reading your design ideas and, as I see it, putting a nitro .40 in the nose and a pair of electrics in the wings is asking for problems. If one of the electric motors fail, you will see your design flat spin into the ground unless you're very careful. If one fails during the climb out, you may not have time to react. Something else to consider is that you are looking at having to carry a lot of weight, being both the electric motor battery packs and nitro fuel just for starters. You also have to consider the weight of a throttle servo for the nitro motor as well as twin electronic speed controls. A Futaba S3004 ball bearing servo weighs weighs 1.31 ounces(37.2 grams) of which you will need four or five minimum, two ESCs that will weigh one ounce each(that is the weight of a Castle Creations BEC2.0 15A BEC rated at 14S, just for sake of figuring weight), two battery packs(one for each motor) at 600 grams each(that's for a Revolectrix 5000mah 4S 70C Graphene Oxide GoPACKS, again just for figuring weight). Now, add to that the variable weight of your nitro fuel and you're carrying a fairly large load, BEFORE you add your receiver and receiver pack.
Just got to thinking. Others have said to buy and build a Sig Kadet Sr. I have to agree with that recommendation. Something to consider is that you are looking at a plane that's 56 inches long with a span of 76 inches at 3.3 pounds. That will be very "short coupled", meaning it could be "twitchy" in flight. The Kadet Sr has a 78 inch span and is 62 inches long. It has an estimated flying weight of 6 pounds, nearly double what you are trying to achieve. That also includes fixed tricycle landing gear so, subtract that and you would be looking at a plane that's still roughly 5.75 pounds and is a proven design. BTW, what I listed as weights in the previous paragraph totaled up to be 275.4 grams or .607 pounds of weight. You still need to add nitro fuel and the weight of your electric motors and all three motor mounts as well as the other hardware needed to that