There is no need to wash your testicles because the urine doesn't reach there. But if urine gets on your testicles you have clean using water three times. If there is no urine on the testicles you should clean your penis using tissue or other materials and then use the water.
The skin that needs to be reached by water during ghusl is the visible, superficial part.
Note that the prophet poured three times water over his head to perform ghusl so you shouldn't waste your time nor water for performing it better than necessary.
Jabir bin `Abdullah said to me, "Your cousin (Hasan bin Muhammad bin Al-Hanafiya) came to me and asked ...
Narrated `Abbad bin Tamim:
My uncle asked Allah's Messenger (ﷺ) about a person who imagined to have passed wind during the prayer. Allah' Apostle replied: "He should not leave his prayers unless he hears sound or smells something."
Sahih al-Bukhari 137
If you are sure that the wind passed then you must leave your Salah even if it’s Fard. Because ...
Regarding your question I would like to quote a Sahih Hadith of Prophet Muhammmad (PBUH)
The deeds (their reward) are dependent on the intentions
The dirt (soil) is not impure according to sharia unless it has urine, poop or other kinds of impurities.
So, insha'Allah your Ghusal will be considered valid.
Allah says in Quran:
in general using soap and a like is ok if you find that water alone doesn't remove the smell so you do a normal shower using these substances (soap and a like) then you do the ghusl and for that here is a good article about how it is done:
An overview of the scholarly views
First of all we need to clarify the scholarly view on madhy: Is it tahir (pure) or is it najis (impure)?
The majority view (some scholars even said it is a consensus) is that it is najis especially based on the ahadith you've quoted saying that one should sprinkle a handful water on what is smeared with it and wash the ...