You seem intent to lengthen only 5 cm (which is modest and probably very safe depending on your starting tibia length).
Purely external lengthening (Ilizarov without nails) remains the safest approach and offers the ability to resolve existing alignment issues, if any.
If you plan on actually stopping at 5 cm; then, it is probably safe enough to leave St. Petersburg during distraction; however, you may need to return for a correction phase after distraction is complete but before your frames are locked for consolidation. You will also likely need to return to remove the frames. When you plan to go beyond 5 cm, you should carefully question whether you should be geographically distant from your medical team because your body will push back very hard against lengthening which can necessitate adjustment to your frames.
If you limit distraction to 5 CM; then, you are probably looking at about 2 months from initial surgery to completion of distraction, another one to two weeks for correction; then, 2-3 months for consolidation -- a doable journey in frames.
You can always elect LATN later if you want to get rid of the frames. Though people on this forum insist LON or LATN causes knee pain, etc., I am aware of no valid, on-point study that supports that notion. I can also attest that I have no knee pain or loss of range of knee motion.
I encourage you to discuss your choices frankly with your MD team. Dr. Kulesh will accept your decisions and make what you want to happen actually happen because he ascribes to the doctrine that "the patient is always right".
However, most patients are dumb as a post when compared to his or her physician. Therefore, it is always important to ask your medical team "what do you advise?" Carefully consider that advice and the underlying rationale before you decide to not follow it.
Best of luck!