Yes, there are companies around the country that can add slide out rooms to RVs. They primarily only add slide outs to expensive Motorhomes that are built on bus chassis.
There is a simple reason that they usually only add slide outs to Motorhomes that are on bus chassis. The bus chassis structure can take the extra weight and structural stress of an added slide out.
I am sure one of these companies could install a slide out on a travel trailer. But first they would have to re-engineer your travel trailer to accept a slide out and it will be very, very, very expensive and you will not recoup any of the cost when you sell your Travel Trailer.
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