Another question, does anyone know, (not hearsay or theoretical) do these laptops only run with 4 SIPs?
Yes.
30 pin SIPs and 30 pin SIMMS (which are electronically identical, it's just the connection type that differs) utilize an 8-bit Data Bus Width. most 386DX and all 486 systems (SX, DX and their clock double/triple variants) use a 32-bit memory address bus, so the SIP/SIMMs (8-bit 30 pin ones) have to be inserted 4x at a time for the system to POST and work properly. This applies for all systems of the 386/486 variety.
TLDR - the memory has to fill out\ the bus width of the memory bus in the computer. 30 pin SIMMS/SIPs are 8-bit, so it takes 4 of them to fill out all the data lines for the 32-bit address bus on 386DX/486 era computers.
Just for a little extra - The theoretical maximum capacity of a 30 pin SIMM/SIP was 16MB, meaning if the chipset and BIOS Code supported it you could get up to 64MB on 30-pin SIP/SIMM RAM, but the majority people could afford were 1MB or 2MB capcity, so 16MB in 30 pin is like a Unicorn or Bigfoot (not the monster truck). My FMA3500C has 4 2MB SIPs in it for 8192K (8MB), the FMA3500 I had around 2003-2005 had 4MB (4x 1MB SIP). There was a guy on here awhile back who also had an FMA3500 and was planning to put 32MB in his system (4x 8MB), wonder what happened with that one.