Possible to Solder top of through-hole header?

Question

I have designed a small 2-sided PCB with through-hole parts, which I plan to have fabbed professionally. Given the lack of space (2"x2" was a design constraint to keep costs low, as I will need a number of these boards), I'm using my through-hole component pins/leads as vias in some cases.

Looking at the render (KiCad), I believe I will be able to solder all of the pins needed on the front of board with one possible exception- I have three 3-pin male headers on the board, which will be used with shunt jumpers. A few of these pins have front-side copper connections and will require front-side soldering. I'm concerned the the plastic spacer on the header will prevent me from soldering the pins on the front side of the board.

With some force, I can slide the spacer up and down the pins, so it occurred to me to:

1. solder the bottom of the header pins
2. slide the spacer up the header pins with small pliers
3. solder the top of the header pins
4. slide the spacer back down into place.

However, I'm concerned about the amount of physical stress this would put on the solder joints. Is this a reasonable method? Is there another method I should use? Or is there an alternate component I should be using?

For reference, here's the render:

The three 3-pin vertical headers on the right side of the board are the components in question.

Answer 1

You shouldn't need to solder on both sides of the board (if I understand what you are asking). Your holes should be plated through (are they?) and therefore they always "act like a via", regardless of whether you solder anything in there or not.

Also, you do know that vias can be really teeny tiny, right? If you're concerned about space efficiency, surface mount parts are your friend.

Answer 2

If I had to solder those on both sides I'd fit them upside-down such that the pins just protrude slightly from the back, solder both sides, and then slide the plastic part down, or pull it off.