If you have 4 of 10kg servoes (aile/elev), and one 20 kilo (rudder) theoretical the peak amps could reach 15A in a snaproll at high speed. 10A peaks is guaranteed reached during hard 3D-flying.
The cheapest, safest and also best choice is to use good NiMh-batteries for receiver And course cables.

Some digital servoes have failsafe, and they might "lock" during hard manouvers because of voltage drops in long cables. Some receivers might also suffer from this...

From experience in the IMAC-club in Norway it s said even the Fromeco-setups is not safe in models above the typical 2,3meter/50ccm size because of voltage drops. Analyzing some crashes with the Weatronic receivers onboard showed excessive volt-drop...

NiCd or NiMH still proves to be safe and cheap