Matched filter for recieved RF digital packet by LPF
Well, you know that the output of your filters shouldn't change faster than a symbol period. You could low-pass filter these to a bandwidth only a bit bigger than the symbol rate.
Since a filter is a linear operation, you can commute it and have it before the matched filters, so you only need one low-pass filter.

smoothly and to do zero crossings in order to choose when I have 0 and 1 in binary

Don't. You should be using a threshold instead of going by zero crossings: the zero is your maximum likelihood decision boundary.
You'll need symbol timing recovery, anyways. Since this is a bursty system, not an &quot;endless&quot; stream of symbols, I'd guess the packet preamble is probably meant to give you that information – use it!
If you can correctly estimate symbol timing from the preamble, your Matched Filters can be coherently decimating down to the symbol rate.