All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
There is no objection to using the means you mentioned provided they do not include any forbidden matters like a woman staying in seclusion with a non-Mahram man, or some of these foreigners being able to look at unveiled Muslim women, or the fact that a woman goes in what can be described as travel without being accompanied by a Mahram.
So, if this technique is free from all that Allah forbids, then there is no harm to use it since the means take the ruling of the intention and objective behind it. Know that the techniques of Da'wah are not limited to what is used in the era of the Prophet as believed by some scholars.
In fact, it is permissible according to the Sharee’ah to use any lawful means such as pamphlets, booklets, magazines, cassettes, seminars, lectures, exhibitions and the similar things that mostly did not exist during the era of the Prophet . If the means of Da'wah were restricted to that which was mentioned in the Quran and Sunnah, then these current means would be unlawful, and no scholar says this.
It should be noted here that the most appropriate way and the one that most suits the Sharee’ah is to limit the Da'wah of men to men and the Da'wah of women to women. Above all, since most of these foreign women are not veiled and they expose their adornments and ‘Awrah. This could lead to the temptation of the Daa’iyah (the caller to Islam) who could be attracted by these things.
Allah knows best.