How to connect a capacitor (high pass 1st order) to a tweeter in series with a full-range speaker?
If you are worried about overloading the amplifier then I wouldn't be overly concerned unless you were intent on playing very loud passages of sound that were exclusively in the low to mid kHz region (not something that normal or even modern music attempts to do).

The 3.9 uF capacitor starts to "bring-in" the tweeter at a few kHz and above so if you are really worried about loading then consider putting an inductor in series with your woofer so that as frequency rises, the woofer is progressively removed from circuit. Something about 1 mH should start reducing the loading effect of the woofer from about 1 kHz upwards.

Alternatively, find one of the several web-site tools that calculates proper cross-over components values and do the job properly.


  I don't have the time to procure other components


Sometimes, you just can't make a silk purse from a sow's ear