I think this is well hashed, but my two cents: each device should ideally have its own fuse, if for no other reason than in keeping with the KISS principle. It is the right way to do it and might save time now, but cause headaches down the road.
True the 14g can handle 15amps, but just barely at 20 feet; but with both pump and heater on, the voltage will drop to around 10.6v or so, effectively causing you higher current than estimated. The pump, although small, does pull more amps upon start up.
Actual current on any device could be less that published, some alot less. Actual measurements should be in order.
XLR Hyperlite 29HFS
Ram 2500 6.7L CTD
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