I can't imagine what it would be like to have another country on our border.
I wouldn't really know what it's like to live right next to another country.
この場合、次のように言うと自然な感じで良いと思います。
ーI can't imagine what it would be like to have another country on our border because Japan is an island nation.
「日本は島国なので、他の国が隣にあるのがどのようなものか想像ができない」
I can't imagine what it would be like ... を使って「感覚がわからない」を表現できます。
ーI wouldn't really know what it's like to live right next to another country.
「他の国の真横に住むのがどんな感じかよくわからない」
I wouldn't really know what it's like ...を使っても「感覚がわからない」を表現できます。
ご参考まで！
I don't know what it's like to live right next to another country.
I don't know what it's like to have another country next to you.
「隣に国があるという感覚がわからない」は英語で「I don't know what it's like to live right next to another country.」と言います。「I don't know what it's like to have another country next to you.」でも通じますがより長い説明があったら「another country next to you」はより自然です。
日本は島国なので、隣接してくにがあるという感覚がどういうものなのかわからない。
Japan is an island, so I don't know what it's like to have another country right next to you.
カナダ 
