Living on the road means we have no normal household expenses.

Aside from providing the basics (ie. listing tool to get the property published to 10+ major sites, scheduling tool to schedule viewings, tenant screening with comprehensive applications -- pulled reports from TransUnion, which include nationwide criminal background checks + credit checks + eviction history, digital lease creation tool, rent collection tool), automated maintenance tracking is key (and having everything in one spot makes a world of difference when it comes time to have a contractor come in and make a repair).

Especially for a higher income household, you can probably buy a nice house in Henderson and fly to CA every month and still save money.

There are a lot of great options out there; aside from providing the basics (ie. listing tool to get the property published to 10+ major sites, scheduling tool to schedule viewings, tenant screening with comprehensive applications which include nationwide criminal background checks + credit checks + eviction history, digital lease creation tool, rent collection tool, and maintenance tracking tool), some services also offer your tenants additional capabilities which makes it an easier sell on your end when getting them to transition over (ie. their ability to report on-time rent payments to the credit bureaus; this can create an added incentive for making sure they pay that rent on time).

I highly recommend David Greene's book, "Buy, Rehab, Rent, Refinance, Repeat" It's the most comprehensive book on the subject

Plus not having to manage the onsite build will be a huge savings.Is there a somewhat comprehensive list of modular home builders?

Is yours a single income household?

I have great credit thanks to the myfico forums and a total credit limit of $14,000 I have no debt and just pay my cell phone bill and the Verizon triple play package bill for my household which totals about $200 a month.

I see ones advertised here and there but where can I find the most comprehensive list? 

It is the most comprehensive I have seen, and my partner is in Detroit as we speak,  setting up an operation there.