All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
First of all, relieving oneself on the in-ground toilets does not necessarily cause the splashing of urine over the body, and it is permissible for you to ask your husband to change the in-ground toilet with a western toilet. Nevertheless, the solution may be achieved by using the in-ground toilet in a way that does not lead to the splashing of impurity over the body and also by not giving way to whispers.
On the other hand, if a person is sure that his body is stained with impurity and this is not just whispers or doubt, then he has to wash the place of impurity. In case one does not know the exact place of impurity while being certain that he is stained with it, then he should wash all the part of the body that he doubts that it is stained with impurity.
In any case, we do not think that there is any hardship in doing this, praise be to Allaah. So, you should take it easy so that Allaah would make matters easy for you. For more benefit, please refer to Fatwa 95214.
Allaah Knows best.