How to load different items into train with 1 inserter?

[pato]

Hello,

i designed a combinator based system to maintain my outpost.
its simply like that:

outpost 1 needs item x
send signal to depot to request item x
item x is requested from requester chest in the amount needed by outpost and loaded into cargo wagon

there is 1 chest and 1 inserter handling multiple items.

the problem is, for example train has 49 items of a type and inserter grabs 3 items at once and can´t load the other 2 items and then it gets stuck.

is there any way to prevent this or to make it grab only 1 item at a time?
or is there a way to limit items stacks to 40 in cargo wagon??

[Deadly-Bagel]

Easiest way I can think of limiting item stacks is to use a belt on a circuit to ensure only one is passed to the inserter at a time, excess can then be removed by an overflow inserter.

Hoping 0.15 will bring a tidier solution for the whole stack size problem.