Hiya Bearcat,
I reckon you may be missing the true purpose of a 'trainer', the very word 'trainer' is tied up in the smoke and mirrors of international salesmanship.
If you want to sell small, light jet aircraft, then they must exist in two versions, the T1 which is a two-seat dual control trainer, and the T1A which is a fully equipped combat fighter.
Then minor air forces will buy simply dozens of T1 trainers on the open market whilst quietly backing them into hangars for retrofitting of missiles and guidance systems onto the conveniently located hard points you have accidentally built into the trainers. At this point the customer might like to maintain the illusion of trainership by using a trainer-like designation, such as T1A.
Nice harmless little things, trainers. No air force can be criticised for buying a couple of hundred of them. Well, except by anyone smart enough to wonder why an air force with no fighters needs so very many trainers.
Bottom line is: nope, you won't sell enough trainers to pay for your production line, but you will sell enough clandestine fighter variants.
Er, somebody may have thought of this already.....