In the datasheet for the MCP1700 family, I found two paragraphs talking about the input capacitance requirement.
3.3 Unregulated Input Voltage Pin (VIN)
Connect VIN to the input unregulated source voltage.
As with all low dropout linear regulators, low source
impedance is necessary for the stable operation of the
LDO. The amount of capacitance required to ensure
low source impedance will depend on the proximity of
the input source capacitors or battery type. For most
applications, 1 μF of capacitance will ensure stable
operation of the LDO circuit. For applications that have
load currents below 100 mA, the input capacitance
requirement can be lowered. The type of capacitor
used can be ceramic, tantalum or aluminum
electrolytic. The low ESR characteristics of the ceramic
will yield better noise and PSRR performance at high
The input of the MCP1700 is connected to the source
of the P-Channel PMOS pass transistor. As with all
LDO circuits, a relatively low source impedance (10 Ω)
is needed to prevent the input impedance from causing
the LDO to become unstable. The size and type of the
required capacitor depend heavily on the input source
type (battery, power supply) and the output current
range of the application. For most applications (up to
100 mA), a 1 μF ceramic capacitor will be sufficient to
ensure circuit stability. Larger values can be used to
improve circuit AC performance.
Neither one says that there is a maximum input capacitance. In fact, section 5.1 says that higher capacitance values will improve AC performance.
I don't believe there is any need to reduce the input capacitance seen by your regulator.
You will probably want to have 1 uF ceramic (low ESR) capacitor immediately at the input pin of the linear regulator, in addition to the higher-value (but higher ESR and ESL) capacitors used at the output of your switching regulator.
If you need a really clean output voltage, you might want to pay attention to what harmonics of the switching frequency your switching regulator produces, and be sure to filter those out if they are above the frequencies where your linear regulator has good line regulation.