I'm not sure how you could put slides out while parked on a city street, if that's what you are talking about - as opposed to renting a spot in a parking garage or something like that. You'd be partially blocking the sidewalk on one side, and inviting the first truck or bus that came along to clip you on the street side. If parked in a parking garage or parking lot, I'd guess you'd have to pay for two spots and park in the middle.
As far as putting it on a Ro-Ro, I'd wonder what the maximum height they can handle before committing to anything. There are people over on Horizon's Unlimited who ship vehicles all over the world. Probably be a good place to ask about that.
http://www.horizonsunlimited.com/hubb/But do keep in mind that many of the more interesting places in the world often can't accommodate the 13 foot or so of height that North
American roads are designed for.
If it was me, I'd be looking at an Alaskan Camper, which lowers the roof as you travel.
http://alaskancampers.com/Though I hear there may be a new camper with that feature coming out.
https://www.supertrampcampers.com/