Flooring Tile - temporary covering for ceramic tile?

Our bathroom has a ceramic tile floor--the tiles are very small. The flooring is original to our 1954 house. The tiles are in great condition, but I hate them as they are impossible to clean. You can't sweep or mop them without making the grout filthy. You literally have to get down on hands & knees to clean the floor, scraping each little line of grout with a toothbrush.

I want something like linoleum, that's easy to clean, but my dh doesn't want to ruin the "integrity" of the bathroom, since it's original to the house. We have compromised in that he has agreed to let me put vinyl flooring or something similar down as long as we could take it up at some unspecified time in the future and the original tiles would still be intact.

Great idea, except the guys at Home Depot tell us it's impossible to lay vinyl flooring down in the bathroom without tearing up the tiles.

Do anyone have any suggestions on maybe....

(1) Some way we could lay the linoleum over the tiles and keep the tiles intact? (My thought was maybe putting subfloor or something between the tiles & vinyl?)

(2) Some other option I might not have thought that is not vinyl flooring but would be able to lay over the tiles and also is easy to clean?

Thanks in advance! :)

In case you have not considered it, you could put new ceramic tile over the old, as long as the old has no cracks or loose tiles. Just clean the old real good and use a modified thinset to set the new. You could go with a 12" tile which would greatly reduce the the grout issue you currently have. Pull the toilet and reseat after new tile, vanity can stay or be pulled, your choice. The new height may be an issue, you will have to decide that.

Dont put vinyl directly over the old tiles as the grout lines will start to show through after awhile. There are self leveling cements used for ceramic but dont know if such an animal exists for vinyl that would bond to the old ceramic. Check with some flooring stores on that.

I'm all for architectural integrity too, (I know exactly what he means). If the tile is what I think it is, they are mosaic tiles, a square in the middle surrounded by 4 rectangles. Anyway they still carry tile like that at the stores, but only in black and white from what I have seen, but maybe there are more colors. What about putting down some new tile like would have been appropriate for the 1954 house. And after you put in the grout, put in grout sealer. I'm not sure if grout sealer is supposed to keep the grout clean, maybe someone else can respond to that.
The tile is unglazed ceramic or porcelain. I did a little bit a web search and didn't find it, but I have spent a good deal of time in ceramic tile stores and have seen it all over. Even if you use white grout, the grout will not be 50 years old, so it can't get gray that fast.

look at fiber floor vinyl, it is a loose lay product.