It should be acceptable to have the survey on one page. OFCCP's primary interest is in ensuring that the entire contents of the survey is maintained. The fact that it is two pages in a printed form is a function of the fonts used, the amount of content included, and so on rather than a function of the desire to have a two-page form. If you want to be entirely safe, you could include the headers above the section of your electronic form with the reasonable accommodation notice. (By the headers, I mean the title "Voluntary Self-Identification of Disability" and the information on the upper right of each each page.) However, so long as you keep all of the original contents of the survey form, you shouldn't have a problem even if the second page headers are omitted. I will note that the fact OFCCP SHOULD accept this approach won't necessarily stop some compliance officer from raising concerns about any reformatting you do. However, this is one of those times that a call to a district director, the regional office, or the national policy office should allow you to do what you have suggested.
You can use this OFCCP audit checklist to ensure you're doing what is required to maintain OFCCP's regulations including VEVRAA, Section 503, and EO 11246. Or request a demo to streamline your compliance and recruiting efforts.