Originally Posted by idroba
Type K soft copper for all the lines. Single flare will be fine. All valves and connections outside, under the rig. As few as possible connections inside the rig. Valves for each appliance are very nice.
Single flares may 'be fine' but they are NOT to current RVIA standards, which require DOUBLE FLARES at all flair fittings when used in LP applications. If you are going to do the job, DO IT RIGHT! A double flair takes a few seconds more to complete than a single one and has much better sealing properties.
Further, I would use rigid black pipe as the main line and branch from that with 'K-type' copper for the branch lines.