...I wish I could make a gif of those two changing every few minutes but I think it would be too large...
Not as large of a file as you might expect...
One thing in your favor with an ani-gif, is that a .gif file is much smaller than a .jpg...of course, the down-side to that is loss of quality/resolution. In the case of these two pix, the image quality is such that a conversion to a .gif is not aparent at all, so it's very do-able!
Here, I've grabbed both of your original sigs, modified the Fw190 one to create one that matches the Bf109 (had to grab the "NJACO" from the Bf109 examples because I don't have that font in my system), and made a nifty little animation that's a total file size of 107Kb...not too bad, really.
I set the delay to 1000 per frame (only two frames) which is around 7 seconds or so, you could go a bit longer if you want. And while I was
REALLY tempted to make the '190 display longer, I was nice and left them both at an even display time...