Short version of problem:

I have LAN network (192.168.100.0/24) and server on ip 192.168.100.5
My friend (town near me - 16km distance) also have LAN network 192.168.200.0/24

One day he take SXT Lite and connect to my network.
Ether1 address on that SXT is 192.168.200.6 (this end is connected to his network)
Wlan1 address on that SXT is 192.168.100.6 (this end is connected to my network)
I have my ISP and he has ISP.

How can we join our two networks so he can access my sever (192.168.100.5), and manage my network via winbox....
Can we just write some rule or rutes to that SXT that connect us?

Better put here scheme, but if network of your freind is directly connected to yours, then simple routing must solve your problem. He setting a route to your lan, you setting a route to his. Then you managing your services in order to allow access to your Tik.

Maybe a candidate for an EOIP tunnel with security option enabled. Assuming you want to do this 16km apart. In this regard it will be like he is on your LAN and thus no external access to your router has to be made (better security).

first, thx for quick answers

I upload scheme with all data that I think you may need, and before anyone answer the main question is where i do put route
in main mt
or in groove
or in sxt lite?
Only main MT contains routes, others have only dynamic routes
I have tried to write some routes which I find in solutions on net but it did not have any results.

Thx in advance