Hello fellow banjo players

I just finished my first musical instrument. A banjo with a skateboard fretboard and a tambourine as a resonator. I have never build an instrument before. Nor can I play anything but a flute back from school. Way back from school.

The banjo is a 4 stringer. 19 frets. The scale lenght is 25" (64cm to be precise) and a 10" tambourine with a plastic skin(head). I got some Deering Tenor strings 0.010, 0.016, 0.024, and 0.030w. I want to tune it to DGBE.

Now my question and my problem:

When tuning I realized I had to turn the pegs so much I fear of breaking them. Also the skin of the tambourine is dented pretty hard. I even fear of breaking this.I guess it is pushed down by the bridge around 1/4". (6-7mm).

Is this normal? Should I use other strings? Or can I just put a wider space under the bridge so that the presure is distributed more evenly?

I also have a backup set of 5 strings Medium from Deering. 0.010, 0.12, 0.16, 0.024w and 0.010.

Before I installed the plastic skin tambourine I had a cheap natural skin tambourine for 10$ but after one hour with strings setup the skin tore through the pins on the side and got loose a little so I decided to replace it.

Old tambourine with damaged skin. The wood also seemed very cheap.

New banjo with plastic skin tambourine

In this picture the strings a relaxed and far from being in tune.