I think the key would be tailoring the Georgian Armed forces for defence of Georgia rather than to be jack of all trades. This would mean getting rid of Air Force aircraft and Navy combat ships as they just ate budget instead of providing defense capabilities. Get rid of armor forces as the budget is too small for them. Instead, focus on key systems capable of hurting invader.
This would be my suggestion:
Overall:
-Focus on giving the invader large initial losses in order to create an impression of Georgia capable of resisting an invader and also creating a threshold of attack.
Naval defence:
-No surface combatants, just police and coast guard craft
-Modern SSM battery (RBS-15, Exocet or something similar, truck mounted) with coastal radar and opto-electronic surveillance system.
-Some heavy ATGM's (Hellfire, Spike LR etc.) for local coastal defence. Works great on armor too
-Get training help from Norway or Sweden for coastal defence
Air defence:
-Sell the aircraft, sell most of the helicopters. No use in high threat environment.
-Leave, say, 4 Mi-24's and 8 Mi-8's for utility and special forces operations and OPFOR roles. Upgrade them to borg level.
-Focus on SAM's. Georgia is a very small country. SAM's are good enough, survivable and cheap. Imagine what Georgian AD had been capable of if resources were not wasted on aircraft and helos.
Ground forces.
-Sell tanks and BMP's, say, sans a company each for OPFOR duties.
-Key combat arms: Infantry and artillery. Focus.
-Focus on defence: Buy good ATGM's and thermal vision equipment to build a defensive network based on independent small combat units. Key weapon systems: ATGM's, machine guns, sniper rifles. Back them up with quality artillery (which Georgia, in OTL, had, but did not use to best effect). Link everything up with quality comms system. Train. Contact Hezbollah for expert advice

-Develop a doctrine in which artillery can support the independent small combat units. Georgia is a small country in which modern artillery range is capable of overlapping a large number of territory. Train.