In the spring of 1944 with the Crossbow campaign well underway, Oberst Schmalschlager's team had developed a new simplified site system. The firing sites were configured with an absolute minimum of permanent structures. Basic pilings for the launch ramp, a flat platform for the steam generator trolley, and a foundation for the non-magnetic guidance shed were made from concrete. The new sites were generally positioned near French farms where the existing buildings could be used for crew accommodation and storage. Certain of the specialized buildings such as the navigation correction building used prefabricated wooden sheds instead of concrete structures. The distinctive ski buildings were not used and missiles were either stored in available buildings or left under camouflage nets. When time permitted, some small structures were built, especially the steam generator preparation shed, workshops for preparing the missile, fuel storage sheds, and the launch bunker near the catapult, and in some cases, prefabricated structures were used. It took a work party of 40 men only about two weeks to construct such a site.
None of these buildings were especially conspicuous, and the new sites proved to be almost invisible to air detection until the launch ramps began to be erected in June 1944. To prevent their identification by the French resistance, the construction was undertaken solely by German military units, the Luftwaffe's Bau Pioneer Battalion Luftgau Belgien-Nord Frankreich (Belgium North France Air Command Engineer Construction Battalion), and the Army's Sonder Pioneer-Stab Frisch (AOK 15) in the Pas-de-Calais and Sonder PioneerStab Berger (AOK 7) in Normandy. Since these units did not have enough troops to carry out the work, they employed convict labor for much of the construction on the assumption that the prisoners' contact with the outside could be restricted. The Walter catapult ramp took about seven to eight days to erect, and were only brought to the site at the start of the missile campaign.
A network of local caves, tunnels, and mines was taken over for use as improvised ordnance storage areas. In total, the "Operational Site System" consisted of five launch sites (Feuerstellungen) for each launch battery plus a support site, for a total of 80 launch sites and 16 support sites, located from Calais westward into lower Normandy. The original "ski sites" were then called Stellungen alter Bauart (old-pattern sites) while the new simplified sites were called Einsatz Stellungen (special sites).